When Cogl is compiled with support for both the GL and GLES drivers it
only includes the GL header and not the GLES header. That means in
that case it would not compile in the code for the
GL_EXT_discard_framebuffer extension even though it could be used on
the GLES driver. This patch makes it use the standard names for the
GL_COLOR, GL_STENCIL etc names instead of the _EXT suffixed names and
manually defines them if we are using the GLES headers. That way the
discard code can be used unconditionally.
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit 59c30292d0f3c28d6e0e08bc5bf3b4b10545d856)
f79e78f648