patch 8.1.1961: more functions can be used as a method

Problem:    More functions can be used as a method.
Solution:   Allow more functions to be used as a method.  Add a test for
            mapcheck().
diff --git a/src/testdir/test_getcwd.vim b/src/testdir/test_getcwd.vim
index e732546..b1470d7 100644
--- a/src/testdir/test_getcwd.vim
+++ b/src/testdir/test_getcwd.vim
@@ -35,7 +35,7 @@
   " we start from a clean state.
   call delete("Xtopdir", "rf")
   new
-  call mkdir('Xtopdir')
+  eval 'Xtopdir'->mkdir()
   cd Xtopdir
   let g:topdir = getcwd()
   call mkdir('Xdir1')