Revert "gallivm: Don't use llvm.x86.avx.max/min.ps.256 inadvertently."
Revert "gallivm: Don't use llvm.x86.avx.max/min.ps.256 inadvertently."

This reverts commit bf2edc776b02a2a63862bf69a23adf666ecfcc57.

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