patch 8.2.4239: build fails with unusual configuration

Problem:    Build fails with unusual configuration.
Solution:   Adjust #ifdef. (closes #9651)
diff --git a/src/testing.c b/src/testing.c
index 4e688a7..9367f3c 100644
--- a/src/testing.c
+++ b/src/testing.c
@@ -1345,7 +1345,7 @@
     void
 f_test_gui_tabline_event(typval_T *argvars UNUSED, typval_T *rettv UNUSED)
 {
-# ifdef FEAT_GUI
+# ifdef FEAT_GUI_TABLINE
     int	tabnr;
 
     if (check_for_number_arg(argvars, 0) == FAIL)
@@ -1361,7 +1361,7 @@
     void
 f_test_gui_tabmenu_event(typval_T *argvars UNUSED, typval_T *rettv UNUSED)
 {
-# ifdef FEAT_GUI
+# ifdef FEAT_GUI_TABLINE
     int	tabnr;
     int	event;