Bug 1202 - Add support of Adaptive Vsync via [GLX|WGL]_EXT_swap_control_tear

[GLX|WGL]_EXT_swap_control_tear extensions support
asynchronous buffer swaps, i.e. adaptive Vsync.

<https://www.opengl.org/wiki/SwapInterval_aka_vsync#Adaptive_Vsync>
<https://www.opengl.org/registry/specs/EXT/wgl_swap_control_tear.txt>
<https://www.opengl.org/registry/specs/EXT/glx_swap_control_tear.txt>

<http://keithp.com/blogs/async_flip/>

The extensions utilizes a negative interval value,
enabling late swaps to occur without synchronization to the video frame.

Hence '-1' has new semantics, previously it was the 'default value'
of 'untouched vsync interval'.

New default is:
  - 0 for unrealized context
  - 1 for realized context

+++

It requires [GLX|WGL]_EXT_swap_control,
hence we shall ensure to use use this extension
in the implementation of GLContext.setSwapInterval(..).

+++

Mesa3D seems to support GLX_SGI_swap_control only.

+++

Implemented on Windows and X11.

+++

On GNU/Linux using NVidia driver w/ my setup(*), sadly the query
  GLX.glXQueryDrawable(displayHandle, drawable.getHandle(), GLX.GLX_LATE_SWAPS_TEAR_EXT, val);
always returns zero here, indicating async vsync is not supported.

(Queried the attribute for every frame in windowed or fullscreen mode)

Fullscreen
(*)
  - Debian 8
  - Kernel 3.16
  - KDE/Kwin
  - GL Version     4.5 (Core profile, arb, compat[ES2, ES3, ES31], FBO, hardware) - 4.5.0 NVIDIA 355.06 [GL 4.5.0, vendor 355.6.0 (NVIDIA 355.06)]
  - GL_RENDERER    GeForce GTX 660/PCIe/SSE2
  - Samsung U28D590 (DFP-4): Internal DisplayPort

+++

1 files changed, 6 insertions, 0 deletions

diff --git a/src/jogl/classes/jogamp/opengl/GLXExtensions.java b/src/jogl/classes/jogamp/opengl/GLXExtensions.java
index 9325c6f68..db4757e4d 100644
--- a/src/jogl/classes/jogamp/opengl/GLXExtensions.java
+++ b/src/jogl/classes/jogamp/opengl/GLXExtensions.java
@@ -34,4 +34,10 @@ public class GLXExtensions {
   public static final String GLX_MESA_swap_control           = "GLX_MESA_swap_control";
   public static final String GLX_SGI_swap_control            = "GLX_SGI_swap_control";
   public static final String GLX_NV_swap_group               = "GLX_NV_swap_group";
+
+  public static final String GLX_EXT_swap_control            = "GLX_EXT_swap_control";
+  public static final String GLX_EXT_swap_control_tear       = "GLX_EXT_swap_control_tear";
+
+  public static final String WGL_EXT_swap_control            = "WGL_EXT_swap_control";
+  public static final String WGL_EXT_swap_control_tear       = "WGL_EXT_swap_control_tear";
 }