i965: Set the signed/unsigned type bit in Gen4/5 math messages.

It never mattered before since we only did floating point math.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Tested-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/mesa/drivers/dri/i965/brw_eu_emit.c

@@ -1533,7 +1533,7 @@ void brw_math( struct brw_compile *p,
       brw_set_math_message(p,
 			   insn,
 			   function,
-			   BRW_MATH_INTEGER_UNSIGNED,
+			   src.type == BRW_REGISTER_TYPE_D,
 			   precision,
 			   saturate,
 			   data_type);