i965/blorp: Skip re-emitting urb config whenever possible
i965/blorp: Skip re-emitting urb config whenever possible

Otherwise clearing with blorp will regress performance in some
synthetic test cases.

v2: Used vsize >= 2 instead of vsize > 0, and updated the comment.
    Review by Ken in one of the earlier patches revealed this.

Signed-off-by: Topi Pohjolainen <749697f19798b7f640b17221fd283b903825f071@intel.com>
Reviewed-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler