patch 9.0.1769: executable() ignoring symlinks on Windows

Problem:  executable() ignoring symlinks on Windows
Solution: resolve reparse points

closes: #12562

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: AmberArr <me@frost.moe>
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 60e9921..a500b73 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1818,6 +1818,10 @@
     let [pathext, $PATHEXT] = [$PATHEXT, '.com;.exe;.bat;.cmd']
     call assert_equal(notepadbat, exepath('notepad'))
     let $PATHEXT = pathext
+    " check for symbolic link
+    execute 'silent !mklink np.bat "' .. notepadbat .. '"'
+    call assert_equal(1, executable('./np.bat'))
+    call assert_equal(1, executable('./np'))
     bwipe
     eval 'Xnotedir'->delete('rf')
   elseif has('unix')