patch 8.1.0553: it is not easy to edit a script that was sourced

Problem:    It is not easy to edit a script that was sourced.
Solution:   Add a count to ":scriptnames", so that ":script 40" edits the
            script with script ID 40.

src/version.c

@@ -792,6 +792,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    553,
 /**/
     552,
 /**/