Save and restore front colors on backfacing triangles rather than trying to pull them again from the VB pointers.  Avoids stride issues.
Save and restore front colors on backfacing triangles rather than trying to
pull them again from the VB pointers.  Avoids stride issues.

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