D3D8: Add GL_ARB_multisample definitions

[H. Verbeet]

This *should* be the correct way to fix this compile error:
http://www.winehq.org/pipermail/wine-devel/2006-January/044259.html
However, since I don't have OpenGL headers that old, I'm unable to
reproduce the problem, let alone verify that this patch fixes it.
Nevertheless, at the very least it shouldn't cause problems for people
with more recent OpenGL headers.

Changelog:
  - Add GL_ARB_multisample definitions
-------------- next part --------------
diff --git a/dlls/d3d8/d3dcore_gl.h b/dlls/d3d8/d3dcore_gl.h
index 6bacc5f..31d72ae 100644
--- a/dlls/d3d8/d3dcore_gl.h
+++ b/dlls/d3d8/d3dcore_gl.h
@@ -599,6 +599,21 @@ typedef void (APIENTRY * PGLFNGETCOMBINE
 #define GL_COORD_REPLACE_ARB              0x8862
 #endif
 
+/* GL_ARB_multisample */
+#ifndef GL_ARB_multisample
+#define GL_ARB_multisample 1
+#define GL_MULTISAMPLE_ARB                0x809D
+#define GL_SAMPLE_ALPHA_TO_COVERAGE_ARB   0x809E
+#define GL_SAMPLE_ALPHA_TO_ONE_ARB        0x809F
+#define GL_SAMPLE_COVERAGE_ARB            0x80A0
+#define GL_SAMPLE_BUFFERS_ARB             0x80A8
+#define GL_SAMPLES_ARB                    0x80A9
+#define GL_SAMPLE_COVERAGE_VALUE_ARB      0x80AA
+#define GL_SAMPLE_COVERAGE_INVERT_ARB     0x80AB
+#define GL_MULTISAMPLE_BIT_ARB            0x20000000
+#endif
+typedef void (APIENTRY * PGLFNSAMPLECOVERAGEARBPROC) (GLclampf value, GLboolean invert);
+
 /*******
  * OpenGL Official Version 
  *  defines