i965: Fix RECT shadow sampling by not losing the other texcoords.
i965: Fix RECT shadow sampling by not losing the other texcoords.

Bug #20821
(cherry picked from commit 191e028de20b2f954621b652aa77b06d0e93652a)

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