glsl: Fail the build if the grammar contains shift/reduce errors.
glsl: Fail the build if the grammar contains shift/reduce errors.

When working on a parser, it's very easy to accidentally introduce
new shift/reduce conflicts.  Failing the build guarantees they'll
be noticed and fixed.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Chris Forbes <5dcac483e7a6e31a5cbe89f38cc69dff8ee93dac@ijw.co.nz>

mcanthony/glsl-optimizer,mcanthony/glsl-optimizer,benaadams/glsl-optimizer,mapbox/glsl-optimizer,wolf96/glsl-optimizer,dellis1972/glsl-optimizer,djreep81/glsl-optimizer,bkaradzic/glsl-optimizer,mcanthony/glsl-optimizer,zeux/glsl-optimizer,mapbox/glsl-optimizer,wolf96/glsl-optimizer,benaadams/glsl-optimizer,mapbox/glsl-optimizer,jbarczak/glsl-optimizer,tokyovigilante/glsl-optimizer,dellis1972/glsl-optimizer,bkaradzic/glsl-optimizer,zeux/glsl-optimizer,jbarczak/glsl-optimizer,tokyovigilante/glsl-optimizer,benaadams/glsl-optimizer,jbarczak/glsl-optimizer,wolf96/glsl-optimizer,zz85/glsl-optimizer,benaadams/glsl-optimizer,wolf96/glsl-optimizer,dellis1972/glsl-optimizer,djreep81/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,bkaradzic/glsl-optimizer,zz85/glsl-optimizer,benaadams/glsl-optimizer,benaadams/glsl-optimizer,djreep81/glsl-optimizer,dellis1972/glsl-optimizer,zz85/glsl-optimizer,mcanthony/glsl-optimizer,tokyovigilante/glsl-optimizer,metora/MesaGLSLCompiler,jbarczak/glsl-optimizer,tokyovigilante/glsl-optimizer,bkaradzic/glsl-optimizer,mapbox/glsl-optimizer,metora/MesaGLSLCompiler,djreep81/glsl-optimizer,dellis1972/glsl-optimizer,bkaradzic/glsl-optimizer,mapbox/glsl-optimizer,wolf96/glsl-optimizer,zz85/glsl-optimizer,mcanthony/glsl-optimizer,zeux/glsl-optimizer,tokyovigilante/glsl-optimizer,zeux/glsl-optimizer,zz85/glsl-optimizer,zeux/glsl-optimizer,metora/MesaGLSLCompiler