patch 8.2.3108: test for remote_foreground() fails

Problem:    Test for remote_foreground() fails. (Elimar Riesebieter)
Solution:   Check that $DISPLAY is set. (Christian Brabandt)
diff --git a/src/version.c b/src/version.c
index 060c2e7..9b1ac9a 100644
--- a/src/version.c
+++ b/src/version.c
@@ -756,6 +756,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    3108,
+/**/
     3107,
 /**/
     3106,