mesa: use C locale for _mesa_strtod()
mesa: use C locale for _mesa_strtod()

_mesa_strtod() is used for shader/program parsing where the decimal
point character is always '.'  Use strtod_l() with a "C" locale to
ensure correct string->double conversion when the actual locale uses
another character such as ',' for the decimal point.

Fixes bug 24531.

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