patch 8.2.1527: Vim9: cannot use a function name at script level

Problem:    Vim9: cannot use a function name as a function reference at script
            level.
Solution:   Check if a name is a function name. (closes #6789)

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1527,
 /**/
     1526,
 /**/