patch 8.1.1675: listener list not correctly updated on listener_remove()

Problem:    Listener list not correctly updated on listener_remove().
Solution:   Only set "prev" when not removing a listener.  Return one if the
            listener was found and removed.

src/version.c

@@ -777,6 +777,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1675,
 /**/
     1674,
 /**/