patch 8.2.2415: no way to check for the cmdwin feature

Problem:    No way to check for the cmdwin feature, cmdline_hist is now always
            enabled.
Solution:   Add has('cmdwin') support. Skip arglist test on Windows
            temporarily.
diff --git a/src/testdir/test_normal.vim b/src/testdir/test_normal.vim
index d2f1fab..8aef41d 100644
--- a/src/testdir/test_normal.vim
+++ b/src/testdir/test_normal.vim
@@ -2584,9 +2584,11 @@
   call assert_false(&insertmode)
   call assert_beeps("normal! \<C-\>\<C-A>", 'xt')
 
-  " Using CTRL-\ CTRL-N in cmd window should close the window
-  call feedkeys("q:\<C-\>\<C-N>", 'xt')
-  call assert_equal('', getcmdwintype())
+  if has('cmdwin')
+    " Using CTRL-\ CTRL-N in cmd window should close the window
+    call feedkeys("q:\<C-\>\<C-N>", 'xt')
+    call assert_equal('', getcmdwintype())
+  endif
 
   " clean up
   bw!