glsl: Make gl_TexCoord compatibility-only

glsl: Make gl_TexCoord compatibility-only

gl_TexCoord was deprecated in GLSL 1.30.  In GLSL 1.40 it was marked
as ARB_compatibility-only, and in GLSL 1.50 and above it was marked as
only appearing in the compatibility profile.  It has never appeared in
GLSL ES.

However, Mesa erroneously included it in all desktop versions of GLSL,
even versions 1.40 and 1.50 (which do not currently support the
compatibility profile).  This patch makes gl_TexCoord available in the
compatibility profile (and GLSL versions 1.30 and prior) only.

NOTE: although this is a simple bug fix, it probably isn't sensible to
cherry-pick it to stable release branches, since its only effect is to
cause incorrectly-written shaders to fail to compile.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>