patch 9.0.0633: FEAT_TITLE was removed but is still used

Problem:    FEAT_TITLE was removed but is still used.
Solution:   Remove FEAT_TITLE. (Naruhiko Nishino, closes #11256)
diff --git a/src/gui_gtk_x11.c b/src/gui_gtk_x11.c
index 945cb09..736d1c7 100644
--- a/src/gui_gtk_x11.c
+++ b/src/gui_gtk_x11.c
@@ -6159,7 +6159,7 @@
     return FAIL;
 }
 
-#if defined(FEAT_TITLE) || defined(FEAT_EVAL) || defined(PROTO)
+#if defined(FEAT_EVAL) || defined(PROTO)
 /*
  * Return the text window-id and display.  Only required for X-based GUI's
  */