i965: Use WARN_ONCE for the single-primitive-exceeded-aperture message.

This makes it show up via ARB_debug_output and is also less code.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>

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

@@ -520,15 +520,10 @@ retry:
 	    fail_next = true;
 	    goto retry;
 	 } else {
-	    if (intel_batchbuffer_flush(brw) == -ENOSPC) {
-	       static bool warned = false;
-
-	       if (!warned) {
-		  fprintf(stderr, "i965: Single primitive emit exceeded"
-			  "available aperture space\n");
-		  warned = true;
-	       }
-	    }
+            int ret = intel_batchbuffer_flush(brw);
+            WARN_ONCE(ret == -ENOSPC,
+                      "i965: Single primitive emit exceeded "
+                      "available aperture space\n");
 	 }
       }