i965/fs: Add dump_instruction() support for ARF destinations.
i965/fs: Add dump_instruction() support for ARF destinations.

CMP instructions use BRW_ARF_NULL as a destination.  Prior to this
patch, dump_instruction() decoded the destination as "???".

Now it decodes BRW_ARF_NULL as "(null)" and other ARFs numerically.

Signed-off-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>
Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>

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