r600: set mega fetch count to 16 for gs copy shader
r600: set mega fetch count to 16 for gs copy shader

Seems like MFC should be set for this shader.

Signed-off-by: Dave Airlie <f2295d84e358395675bc8031be58672073ae065e@redhat.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler