Remove duplicate client queue (mruq); instead, remove and take the

global Clientq and place it inside screen_ctx since every client belongs
to a screen, then use the same per screen clientq to track stacking
order (the sole reason for mruq).

screen.c

@@ -40,7 +40,7 @@ screen_init(int which)
 
 	sc = xcalloc(1, sizeof(*sc));
 
-	TAILQ_INIT(&sc->mruq);
+	TAILQ_INIT(&sc->clientq);
 	TAILQ_INIT(&sc->regionq);
 
 	sc->which = which;