move keymap copy to event processing, from enqueuing

Move the keymap copying to event processing time (in
ProcessInputEvents), instead of being at event enqueuing time.
Break SetCore{Pointer,Keyboard} out into separate functions.
Change mieqEnqueue to take a device pointer, that asks for the
_original_ device associated with this event.

mi/mi.h

@@ -173,6 +173,7 @@ extern Bool mieqInit(
 );
 
 extern void mieqEnqueue(
+    DeviceIntPtr /*pDev*/,
     xEventPtr /*e*/
 );