i965/gs: Set number of control data bits for stream mode.
i965/gs: Set number of control data bits for stream mode.

If the geometry shader is indeed using streams then we need 2 control data
bits per vertex for the StreamID. If the shader is not using streams then
we don't need control data bits.

Reviewed-by: Chris Forbes <5dcac483e7a6e31a5cbe89f38cc69dff8ee93dac@ijw.co.nz>
Reviewed-by: Ian Romanick <2b237cafb16dc45038e85df6c85e74e6d899eba9@intel.com>

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