core: Exit early on keybindings if this is a wayland compositor

Fixes a thinko in commit 79b5ece2. It is meant to bail out early
on issuing X11 passive grabs if the compositor is a wayland one,
but this condition was inverted.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/721

src/core/keybindings.c

@@ -1570,7 +1570,7 @@ meta_window_grab_keys (MetaWindow  *window)
   MetaDisplay *display = window->display;
   MetaKeyBindingManager *keys = &display->key_binding_manager;
 
-  if (!meta_is_wayland_compositor ())
+  if (meta_is_wayland_compositor ())
     return;
   if (window->all_keys_grabbed)
     return;