win: Fix opaque regions for Wayland

In Wayland, an opaque window can still have shadow borders, and
only needs to set the opaque_region appropriately. In X on the
other hand, a window needs to be flagged as alpha in order to be
properly blended (otherwise you'd get black borders).

Thanks Derek for the report!

This fixes c91360fcbd

src/lib/elementary/efl_ui_win.c

@@ -414,10 +414,10 @@ _elm_win_apply_alpha(Eo *obj, Efl_Ui_Win_Data *sd)
      }
    else
      {
-        enabled |= (sd->csd.need && !sd->fullscreen);
 #ifdef HAVE_ELEMENTARY_X
         if (sd->x.xwin)
           {
+             enabled |= (sd->csd.need && !sd->fullscreen);
              if (enabled)
                {
                   if (!ecore_x_screen_is_composited(0))