x11: Support the all-resize cursor

This is an alternative name for the move cursor.

(cherry picked from commit 1eaa4eb4051c42242f1eadd2d5e45b45a94d2e8d)

gdk/x11/gdkcursor-x11.c

@@ -650,6 +650,7 @@ static const struct {
   { "nwse-resize",  "bd_double_arrow" },
   { "zoom-in",      "left_ptr" },
   { "zoom-out",     "left_ptr" },
+  { "all-resize",   "move" }, /* not CSS, but we want to guarantee it anyway */
   { NULL, NULL }
 };