patch 8.0.0276: unnecessary #ifdefs

Problem:    Checking for FEAT_GUI_GNOME inside GTK 3 code is unnecessary.
Solution:   Remove the #ifdef. (Kazunobu Kuriyama)
diff --git a/src/version.c b/src/version.c
index d8b82a8..8aeb688 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    276,
+/**/
     275,
 /**/
     274,