libweston: Bring back 'weston_output_move'

For supporting output layout, compositors need the ability to manually set the
'weston_output' by 'weston_output_move'.

Signed-off-by: sichem <sichem.zh@gmail.com>

include/libweston/libweston.h

@@ -2013,6 +2013,9 @@ weston_output_init(struct weston_output *output,
 		   struct weston_compositor *compositor,
 		   const char *name);
 
+void
+weston_output_move(struct weston_output *output, int x, int y);
+
 int
 weston_output_enable(struct weston_output *output);
 

libweston/backend.h

@@ -135,9 +135,6 @@ weston_output_init(struct weston_output *output,
 void
 weston_output_damage(struct weston_output *output);
 
-void
-weston_output_move(struct weston_output *output, int x, int y);
-
 void
 weston_output_release(struct weston_output *output);