patch 8.1.0711: test files still use function!

Problem:    Test files still use function!.
Solution:   Remove the exclamation mark.  Fix overwriting a function.
diff --git a/src/testdir/test_listlbr.vim b/src/testdir/test_listlbr.vim
index 7856ee8..29e797d 100644
--- a/src/testdir/test_listlbr.vim
+++ b/src/testdir/test_listlbr.vim
@@ -13,9 +13,9 @@
   return ScreenLines(a:lnum, a:width)
 endfunction
 
-function! s:compare_lines(expect, actual)
+func s:compare_lines(expect, actual)
   call assert_equal(join(a:expect, "\n"), join(a:actual, "\n"))
-endfunction
+endfunc
 
 function s:test_windows(...)
   call NewWindow(10, 20)