patch 8.0.1021: older Gnome terminal still echoes t_RC

Problem:    Older Gnome terminal still echoes t_RC. (Fracois Ingelrest)
Solution:   Check for version > 3000 instead of 4000.
diff --git a/src/version.c b/src/version.c
index e67ade3..e0be7aa 100644
--- a/src/version.c
+++ b/src/version.c
@@ -770,6 +770,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1021,
+/**/
     1020,
 /**/
     1019,