desktop-shell: Pass a flag bitmask instead of bool to activate()

Although it currently only has one available flag, but that'll change.

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>
Reviewed-by: Derek Foreman <derekf@osg.samsung.com>
Acked-by: Peter Hutterer <peter.hutterer@who-t.net>

libweston/compositor.h

@@ -1124,6 +1124,11 @@ enum weston_key_state_update {
 	STATE_UPDATE_NONE,
 };
 
+enum weston_activate_flag {
+	WESTON_ACTIVATE_FLAG_NONE = 0,
+	WESTON_ACTIVATE_FLAG_CONFIGURE = 1 << 0,
+};
+
 void
 weston_version(int *major, int *minor, int *micro);