dispatch: Mark swapped dispatch as _X_COLD

This touches everything that ends up in the Xorg binary; the big missing
part is GLX since that's all generated code. Cuts about 14k from the
binary on amd64.

Signed-off-by: Adam Jackson <ajax@redhat.com>
Reviewed-by: Eric Anholt <eric@anholt.net>

Xi/sendexev.c

@@ -73,7 +73,7 @@ extern int lastEvent;           /* Defined in extension.c */
  *
  */
 
-int
+int _X_COLD
 SProcXSendExtensionEvent(ClientPtr client)
 {
     CARD32 *p;