trace: Fix set_constant_buffer dumping.
trace: Fix set_constant_buffer dumping.

We were dumping the trace driver pointer, instead of the pointer from the
underlying pipe driver.

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