if we are saving the pointer location for a specific client, make sure

that if it is not already inbounds, put it in the default location,
which happens to be inbounds.

behavior noticed by Thomas Pfaff while maximizing and un-maximizing a
window, leaving the pointer behind and causing client_cycle() to be a
bit lost.

ok oga@

client.c

@@ -435,6 +435,9 @@ client_ptrsave(struct client_ctx *cc)
 	if (client_inbound(cc, x, y)) {
 		cc->ptr.x = x;
 		cc->ptr.y = y;
+	} else {
+		cc->ptr.x = -1;
+		cc->ptr.y = -1;
 	}
 }