patch 8.0.0983: unnecessary check for NULL pointer

Problem:    Unnecessary check for NULL pointer.
Solution:   Remove the NULL check in dialog_changed(), it already happens in
            dialog_msg(). (Ken Takata)

src/version.c

@@ -769,6 +769,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    983,
 /**/
     982,
 /**/