patch 8.2.4063: Vim9: exported function in autoload script not found

Problem:    Vim9: exported function in autoload script not found. (Yegappan
            Lakshmanan)
Solution:   Use the autoload prefix to search for the function.
diff --git a/src/testdir/test_vim9_import.vim b/src/testdir/test_vim9_import.vim
index ddf5b82..46b826c 100644
--- a/src/testdir/test_vim9_import.vim
+++ b/src/testdir/test_vim9_import.vim
@@ -1146,8 +1146,8 @@
        return 'test'
      enddef
 
-     export func GetSome()
-       return 'some'
+     export func GetMore()
+       return Gettest() .. 'more'
      endfunc
 
      export var name = 'name'
@@ -1163,7 +1163,7 @@
       assert_equal('test', prefixed.Gettest())
       assert_equal('yes', g:prefixed_loaded)
 
-      assert_equal('some', prefixed.GetSome())
+      assert_equal('testmore', prefixed.GetMore())
       assert_equal('name', prefixed.name)
       assert_equal('final', prefixed.fname)
       assert_equal('const', prefixed.cname)
@@ -1173,7 +1173,7 @@
   # can also get the items by autoload name
   lines =<< trim END
       call assert_equal('test', prefixed#Gettest())
-      call assert_equal('some', prefixed#GetSome())
+      call assert_equal('testmore', prefixed#GetMore())
       call assert_equal('name', prefixed#name)
       call assert_equal('final', prefixed#fname)
       call assert_equal('const', prefixed#cname)