st/xorg: fix ureg_DECL_constant() parameters
st/xorg: fix ureg_DECL_constant() parameters

This fixes the compilation errors reported in bug 23945 but someone more
familiar with the code should review for correctness and close the bug
report.

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