opengl: define compatibility constants

OpenGL ES 2 does not necessarily define all these constants, but
supports them as extensions.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/video_output/opengl/gl_common.h

@@ -95,6 +95,58 @@
 # define GL_DYNAMIC_DRAW 0x88E8
 #endif
 
+#ifndef GL_READ_FRAMEBUFFER
+# define GL_READ_FRAMEBUFFER 0x8CA8
+#endif
+
+#ifndef GL_READ_FRAMEBUFFER_BINDING
+# define GL_READ_FRAMEBUFFER_BINDING 0x8CAA
+#endif
+
+#ifndef GL_DRAW_FRAMEBUFFER
+# define GL_DRAW_FRAMEBUFFER 0x8CA9
+#endif
+
+#ifndef GL_DRAW_FRAMEBUFFER_BINDING
+# define GL_DRAW_FRAMEBUFFER_BINDING 0x8CA6
+#endif
+
+#ifndef GL_MULTISAMPLE
+# define GL_MULTISAMPLE 0x809D
+#endif
+
+#ifndef GL_COLOR_ATTACHMENT0
+# define GL_COLOR_ATTACHMENT0 0x8CE0
+#endif
+
+#ifndef GL_COLOR_ATTACHMENT1
+# define GL_COLOR_ATTACHMENT1 0x8CE1
+#endif
+
+#ifndef GL_COLOR_ATTACHMENT2
+# define GL_COLOR_ATTACHMENT2 0x8CE2
+#endif
+
+#ifndef GL_COLOR_ATTACHMENT3
+# define GL_COLOR_ATTACHMENT3 0x8CE3
+#endif
+
+#ifndef GL_COLOR_ATTACHMENT4
+# define GL_COLOR_ATTACHMENT4 0x8CE4
+#endif
+
+#ifndef GL_COLOR_ATTACHMENT5
+# define GL_COLOR_ATTACHMENT5 0x8CE5
+#endif
+
+#ifndef GL_COLOR_ATTACHMENT6
+# define GL_COLOR_ATTACHMENT6 0x8CE6
+#endif
+
+#ifndef GL_COLOR_ATTACHMENT7
+# define GL_COLOR_ATTACHMENT7 0x8CE7
+#endif
+
 #ifndef APIENTRY
 # define APIENTRY
 #endif