patch 8.2.3568: ctrl-hat test fails with Athena and Motif

Problem:    Ctrl-hat test fails with Athena and Motif. (Elimar Riesebieter)
Solution:   Run the test only with GTK. (Dominique Pellé, closes #9069)
diff --git a/src/testdir/test_edit.vim b/src/testdir/test_edit.vim
index 6c76086..0abc47a 100644
--- a/src/testdir/test_edit.vim
+++ b/src/testdir/test_edit.vim
@@ -2037,7 +2037,11 @@
 " Test toggling of input method. See :help i_CTRL-^
 func Test_edit_CTRL_hat()
   CheckFeature xim
-  CheckNotGui " FIXME: why does this test fail when running in the GUI?
+
+  " FIXME: test fails with Athena and Motif GUI.
+  "        test also fails when running in the GUI.
+  CheckFeature gui_gtk
+  CheckNotGui
 
   new