compositor: Change "touched" to bool

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/src/compositor.h b/src/compositor.h
index 203c2fd..a07b51a 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -968,7 +968,7 @@
 	/* Not for long-term storage.  This exists for book-keeping while
 	 * iterating over surfaces and views
 	 */
-	int32_t touched;
+	bool touched;
 
 	void *renderer_state;