patch 8.2.4264: Vim9: can use old style autoload function name

Problem:    Vim9: can use old style autoload function name.
Solution:   Give an error for old style autoload function name.
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 41ba2da..434d49b 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -46,7 +46,7 @@
 
   var lines =<< trim END
       vim9script
-      def script#OnlyCompiled()
+      export def OnlyCompiled()
         g:runtime = 'yes'
         invalid
       enddef
@@ -114,7 +114,7 @@
 
   var lines =<< trim END
       vim9script
-      def scriptX#Function()
+      export def NoFunction()
         # comment
         g:runtime = 'yes'
       enddef
@@ -126,7 +126,7 @@
   lines =<< trim END
       call script#Function()
   END
-  v9.CheckScriptFailure(lines, 'E746:', 2)
+  v9.CheckScriptFailure(lines, 'E117:', 1)
 
   &rtp = save_rtp
   delete(dir, 'rf')