XCB/window: force window provider when libvlc_*_set_xid() is used

We cannot drop the priority to zero. This would break rare but
functional use of `vlc --drawable-xid $WINDOWID`.

modules/video_output/xcb/window.c

@@ -74,6 +74,7 @@ vlc_module_begin ()
     set_subcategory (SUBCAT_VIDEO_VOUT)
     set_capability ("vout window xid", 70)
     set_callbacks (EmOpen, EmClose)
+    add_shortcut ("embed-xid")
 
     add_integer ("drawable-xid", 0, NULL, XID_TEXT, XID_LONGTEXT, true)
         change_volatile ()

src/control/media_player.c

@@ -826,6 +826,7 @@ void libvlc_media_player_set_xwindow( libvlc_media_player_t *p_mi,
                                       uint32_t drawable )
 {
     assert (p_mi != NULL);
+    var_SetString (p_mi, "window", "embed-xid,any");
     var_SetInteger (p_mi, "drawable-xid", drawable);
 }