patch 8.2.3954: Vim9: no error for shadowing if script var is declared later

Problem:    Vim9: no error for shadowing if script var is declared later.
Solution:   Check argument names when compiling a function.

src/version.c

@@ -749,6 +749,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3954,
 /**/
     3953,
 /**/