Bug 1696319 - Stick to GDK_IS_X11_DISPLAY for now, r=stransky

In D106726 this was changed to `GDK_IS_WAYLAND_DISPLAY` as a drive-by
cleanup, in order to eventually support compiling FF without X11 support.
Turns out that was misguided as it breaks compatability with
setups that have GTK compiled without Wayland support.

Stick to `GDK_IS_X11_DISPLAY` until we have a better solution.

Differential Revision: https://phabricator.services.mozilla.com/D107345

widget/GfxInfoX11.cpp

@@ -463,7 +463,7 @@ void GfxInfo::GetData() {
   mAdapterDescription.Assign(glRenderer);
 #ifdef MOZ_WAYLAND
   mIsWayland = gdk_display_get_default() &&
-               GDK_IS_WAYLAND_DISPLAY(gdk_display_get_default());
+               !GDK_IS_X11_DISPLAY(gdk_display_get_default());
   if (mIsWayland) {
     mIsWaylandDRM = GetDMABufDevice()->IsDMABufVAAPIEnabled() ||
                     GetDMABufDevice()->IsDMABufWebGLEnabled() ||