mesa: Fix array out-of-bounds access in _mesa_TexEnvf.
mesa: Fix array out-of-bounds access in _mesa_TexEnvf.

_mesa_TexEnvf calls _mesa_TexEnvfv, which uses the param argument
as an array.
(cherry picked from commit a11d60d14caf8efc07f70af63b57b33273f8cf9b)

bkaradzic/glsl-optimizer,mcanthony/glsl-optimizer,dellis1972/glsl-optimizer,bkaradzic/glsl-optimizer,adobe/glsl2agal,wolf96/glsl-optimizer,metora/MesaGLSLCompiler,adobe/glsl2agal,zeux/glsl-optimizer,bkaradzic/glsl-optimizer,metora/MesaGLSLCompiler,mcanthony/glsl-optimizer,wolf96/glsl-optimizer,djreep81/glsl-optimizer,zz85/glsl-optimizer,bkaradzic/glsl-optimizer,wolf96/glsl-optimizer,tokyovigilante/glsl-optimizer,djreep81/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,dellis1972/glsl-optimizer,jbarczak/glsl-optimizer,mcanthony/glsl-optimizer,tokyovigilante/glsl-optimizer,benaadams/glsl-optimizer,zz85/glsl-optimizer,djreep81/glsl-optimizer,metora/MesaGLSLCompiler,benaadams/glsl-optimizer,mapbox/glsl-optimizer,jbarczak/glsl-optimizer,zz85/glsl-optimizer,mapbox/glsl-optimizer,djreep81/glsl-optimizer,zeux/glsl-optimizer,adobe/glsl2agal,bkaradzic/glsl-optimizer,tokyovigilante/glsl-optimizer,mcanthony/glsl-optimizer,mapbox/glsl-optimizer,KTXSoftware/glsl2agal,KTXSoftware/glsl2agal,jbarczak/glsl-optimizer,adobe/glsl2agal,zz85/glsl-optimizer,dellis1972/glsl-optimizer,zz85/glsl-optimizer,tokyovigilante/glsl-optimizer,KTXSoftware/glsl2agal,benaadams/glsl-optimizer,zeux/glsl-optimizer,KTXSoftware/glsl2agal,zeux/glsl-optimizer,dellis1972/glsl-optimizer,adobe/glsl2agal,jbarczak/glsl-optimizer,dellis1972/glsl-optimizer,benaadams/glsl-optimizer,mapbox/glsl-optimizer,wolf96/glsl-optimizer,mapbox/glsl-optimizer,wolf96/glsl-optimizer,mcanthony/glsl-optimizer,benaadams/glsl-optimizer,jbarczak/glsl-optimizer,KTXSoftware/glsl2agal,tokyovigilante/glsl-optimizer,zeux/glsl-optimizer,benaadams/glsl-optimizer