Clean up includes a bit

Trying out the IWYU tool to only include what's necessary in a given file.
Seems to work decently (it'll miss some headers, suggest unnecessary ones, and
make nonsense suggestions for some things, but overall gives a good starting
point), and helps clean out some headers.

8 files changed, 164 insertions, 111 deletions

diff --git a/OpenAL32/Include/alMain.h b/OpenAL32/Include/alMain.h
index 3487d42e..33b2fc39 100644
--- a/OpenAL32/Include/alMain.h
+++ b/OpenAL32/Include/alMain.h
@@ -1,38 +1,41 @@
 #ifndef AL_MAIN_H
 #define AL_MAIN_H
 
-#include <string.h>
-#include <stdio.h>
-#include <stddef.h>
-#include <stdarg.h>
-#include <assert.h>
-#include <math.h>
-#include <limits.h>
-
-#ifdef HAVE_STRINGS_H
-#include <strings.h>
-#endif
-
+#include <algorithm>
 #include <array>
-#include <vector>
-#include <string>
+#include <atomic>
 #include <chrono>
-#include <algorithm>
+#include <cstdint>
+#include <cstddef>
+#include <memory>
+#include <mutex>
+#include <string>
+#include <utility>
 
 #include "AL/al.h"
 #include "AL/alc.h"
 #include "AL/alext.h"
 
-#include "inprogext.h"
-#include "atomic.h"
-#include "vector.h"
 #include "albyte.h"
 #include "almalloc.h"
 #include "alnumeric.h"
 #include "alspan.h"
-#include "threads.h"
 #include "ambidefs.h"
+#include "atomic.h"
 #include "hrtf.h"
+#include "inprogext.h"
+#include "vector.h"
+
+class BFormatDec;
+struct ALbuffer;
+struct ALeffect;
+struct ALfilter;
+struct BackendBase;
+struct Compressor;
+struct EffectState;
+struct FrontStablizer;
+struct Uhj2Encoder;
+struct bs2b;
 
 
 #ifndef UNUSED
@@ -59,23 +62,6 @@ static const union {
 #endif
 
 
-struct HrtfEntry;
-struct HrtfHandle;
-struct EnumeratedHrtf;
-struct DirectHrtfState;
-struct FrontStablizer;
-struct Compressor;
-struct BackendBase;
-struct ALbuffer;
-struct ALeffect;
-struct ALfilter;
-struct EffectState;
-struct Uhj2Encoder;
-class BFormatDec;
-class AmbiUpsampler;
-struct bs2b;
-
-
 #define MIN_OUTPUT_RATE      8000
 #define DEFAULT_OUTPUT_RATE  44100
 #define DEFAULT_UPDATE_SIZE  882 /* 20ms */
diff --git a/OpenAL32/Include/alu.h b/OpenAL32/Include/alu.h
index 8abfe15f..841e5c03 100644
--- a/OpenAL32/Include/alu.h
+++ b/OpenAL32/Include/alu.h
@@ -1,31 +1,29 @@
 #ifndef _ALU_H_
 #define _ALU_H_
 
-#include <limits.h>
-#include <math.h>
-#ifdef HAVE_FLOAT_H
-#include <float.h>
-#endif
-#ifdef HAVE_IEEEFP_H
-#include <ieeefp.h>
-#endif
-
-#include <cmath>
 #include <array>
+#include <atomic>
+#include <cmath>
+#include <cstddef>
 
-#include "alMain.h"
-#include "alBuffer.h"
+#include "AL/al.h"
+#include "AL/alc.h"
+#include "AL/alext.h"
 
-#include "hrtf.h"
-#include "logging.h"
-#include "math_defs.h"
+#include "alBuffer.h"
+#include "alMain.h"
+#include "almalloc.h"
+#include "alspan.h"
+#include "ambidefs.h"
 #include "filters/biquad.h"
-#include "filters/splitter.h"
 #include "filters/nfc.h"
+#include "filters/splitter.h"
+#include "hrtf.h"
+#include "logging.h"
 
-#include "almalloc.h"
-#include "alnumeric.h"
-#include "alspan.h"
+struct ALbufferlistitem;
+struct ALeffectslot;
+struct BSincTable;
 
 
 enum class DistanceModel;
@@ -34,13 +32,6 @@ enum class DistanceModel;
 #define MAX_SENDS  16
 
 
-struct BSincTable;
-struct ALsource;
-struct ALbufferlistitem;
-struct ALvoice;
-struct ALeffectslot;
-
-
 #define DITHER_RNG_SEED 22222
 
 
diff --git a/OpenAL32/alBuffer.cpp b/OpenAL32/alBuffer.cpp
index a6ed98cc..f20b0aee 100644
--- a/OpenAL32/alBuffer.cpp
+++ b/OpenAL32/alBuffer.cpp
@@ -20,27 +20,39 @@
 
 #include "config.h"
 
-#include <cstdlib>
-#include <cstdio>
-#include <cassert>
-#ifdef HAVE_MALLOC_H
-#include <malloc.h>
-#endif
+#include "alBuffer.h"
 
-#include <tuple>
+#include <algorithm>
 #include <array>
-#include <vector>
+#include <atomic>
+#include <cassert>
+#include <cstdint>
+#include <cstdio>
+#include <cstring>
+#include <iterator>
 #include <limits>
-#include <algorithm>
+#include <memory>
+#include <mutex>
+#include <new>
+#include <utility>
 
+#include "AL/al.h"
+#include "AL/alc.h"
+#include "AL/alext.h"
+
+#include "alError.h"
 #include "alMain.h"
+#include "albyte.h"
 #include "alcontext.h"
-#include "alu.h"
-#include "alError.h"
-#include "alBuffer.h"
-#include "sample_cvt.h"
 #include "alexcpt.h"
+#include "almalloc.h"
+#include "alnumeric.h"
 #include "aloptional.h"
+#include "atomic.h"
+#include "inprogext.h"
+#include "opthelpers.h"
+#include "sample_cvt.h"
+#include "vector.h"
 
 
 namespace {
diff --git a/OpenAL32/alEffect.cpp b/OpenAL32/alEffect.cpp
index 0c4f9e72..2de61019 100644
--- a/OpenAL32/alEffect.cpp
+++ b/OpenAL32/alEffect.cpp
@@ -20,22 +20,33 @@
 
 #include "config.h"
 
-#include <cstdlib>
-#include <cmath>
-#include <cfloat>
+#include "alEffect.h"
 
 #include <algorithm>
+#include <cstdint>
+#include <cstring>
+#include <iterator>
+#include <memory>
+#include <mutex>
+#include <new>
+#include <utility>
 
 #include "AL/al.h"
 #include "AL/alc.h"
+#include "AL/alext.h"
+#include "AL/efx-presets.h"
+#include "AL/efx.h"
 
+#include "alError.h"
 #include "alMain.h"
 #include "alcontext.h"
-#include "alEffect.h"
-#include "alError.h"
 #include "alexcpt.h"
-
+#include "almalloc.h"
+#include "alnumeric.h"
 #include "effects/base.h"
+#include "logging.h"
+#include "opthelpers.h"
+#include "vector.h"
 
 
 const EffectList gEffectList[15]{
@@ -539,8 +550,6 @@ EffectStateFactory *getFactoryByType(ALenum type)
 }
 
 
-#include "AL/efx-presets.h"
-
 #define DECL(x) { #x, EFX_REVERB_PRESET_##x }
 static const struct {
     const char name[32];
diff --git a/OpenAL32/alError.cpp b/OpenAL32/alError.cpp
index a7895fb9..092784c9 100644
--- a/OpenAL32/alError.cpp
+++ b/OpenAL32/alError.cpp
@@ -20,19 +20,32 @@
 
 #include "config.h"
 
+#include "alError.h"
+
+#include <atomic>
 #include <csignal>
 #include <cstdarg>
 #include <cstdio>
+#include <cstring>
+#include <mutex>
 
 #ifdef HAVE_WINDOWS_H
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #endif
 
+#include "AL/al.h"
+#include "AL/alc.h"
+
 #include "alMain.h"
 #include "alcontext.h"
-#include "alError.h"
 #include "alexcpt.h"
+#include "almalloc.h"
+#include "inprogext.h"
+#include "logging.h"
+#include "opthelpers.h"
+#include "vector.h"
+
 
 bool TrapALError{false};
 
diff --git a/OpenAL32/alSource.cpp b/OpenAL32/alSource.cpp
index 498875bf..22c9e2d2 100644
--- a/OpenAL32/alSource.cpp
+++ b/OpenAL32/alSource.cpp
@@ -20,35 +20,56 @@
 
 #include "config.h"
 
-#include <cstdlib>
-#include <climits>
-#include <cfloat>
+#include "alSource.h"
 
+#include <algorithm>
+#include <array>
+#include <atomic>
+#include <cassert>
+#include <chrono>
+#include <climits>
 #include <cmath>
-#include <thread>
+#include <cstdint>
+#include <cstdlib>
+#include <functional>
+#include <iterator>
 #include <limits>
+#include <memory>
+#include <mutex>
+#include <new>
 #include <numeric>
-#include <algorithm>
-#include <functional>
+#include <thread>
+#include <type_traits>
+#include <utility>
 
 #include "AL/al.h"
 #include "AL/alc.h"
+#include "AL/alext.h"
+#include "AL/efx.h"
 
-#include "alMain.h"
-#include "alcontext.h"
-#include "alError.h"
-#include "alSource.h"
+#include "alAuxEffectSlot.h"
 #include "alBuffer.h"
+#include "alError.h"
 #include "alFilter.h"
-#include "alAuxEffectSlot.h"
-#include "ringbuffer.h"
-#include "bformatdec.h"
-
-#include "backends/base.h"
-
-#include "threads.h"
+#include "alMain.h"
+#include "alcontext.h"
 #include "alexcpt.h"
 #include "almalloc.h"
+#include "alnumeric.h"
+#include "alu.h"
+#include "ambidefs.h"
+#include "atomic.h"
+#include "backends/base.h"
+#include "bformatdec.h"
+#include "filters/nfc.h"
+#include "filters/splitter.h"
+#include "inprogext.h"
+#include "logging.h"
+#include "math_defs.h"
+#include "opthelpers.h"
+#include "ringbuffer.h"
+#include "threads.h"
+#include "vector.h"
 
 
 namespace {
diff --git a/OpenAL32/alState.cpp b/OpenAL32/alState.cpp
index 0c447645..f2c38bb2 100644
--- a/OpenAL32/alState.cpp
+++ b/OpenAL32/alState.cpp
@@ -22,17 +22,26 @@
 
 #include "version.h"
 
-#include <stdlib.h>
+#include <atomic>
 #include <cmath>
+#include <cstdlib>
+#include <cstring>
+#include <mutex>
 
+#include "AL/al.h"
+#include "AL/alc.h"
+#include "AL/alext.h"
+
+#include "alError.h"
 #include "alMain.h"
 #include "alcontext.h"
-#include "alu.h"
-#include "alError.h"
 #include "alexcpt.h"
+#include "almalloc.h"
 #include "alspan.h"
-
-#include "backends/base.h"
+#include "alu.h"
+#include "atomic.h"
+#include "inprogext.h"
+#include "opthelpers.h"
 
 
 namespace {
diff --git a/OpenAL32/event.cpp b/OpenAL32/event.cpp
index 2ee296b0..dfffea9f 100644
--- a/OpenAL32/event.cpp
+++ b/OpenAL32/event.cpp
@@ -2,18 +2,30 @@
 #include "config.h"
 
 #include <algorithm>
+#include <atomic>
+#include <cstring>
+#include <exception>
+#include <memory>
+#include <mutex>
+#include <new>
+#include <string>
+#include <thread>
 
-#include "AL/alc.h"
 #include "AL/al.h"
-#include "AL/alext.h"
+#include "AL/alc.h"
 
+#include "alError.h"
 #include "alMain.h"
+#include "albyte.h"
 #include "alcontext.h"
-#include "alError.h"
-#include "alAuxEffectSlot.h"
+#include "alexcpt.h"
+#include "almalloc.h"
+#include "effects/base.h"
+#include "inprogext.h"
+#include "logging.h"
+#include "opthelpers.h"
 #include "ringbuffer.h"
 #include "threads.h"
-#include "alexcpt.h"
 
 
 static int EventThread(ALCcontext *context)