swrast: Set vp_override flag during DrawPixels
swrast: Set vp_override flag during DrawPixels

Obviously, the color of fragments produced by DrawPixels is not constant,
even if the current vertex array / vertex program state indicates that the
color for normal rendering will be constant. Therefore, we need to override
certain optimisations that have been added to texenvprogram.c

Signed-off-by: Nicolai Haehnle <1d0b47a508f04184301062f109cd46e4b3383bfb@gmail.com>

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