vim-patch:8.1.2108: cannot close the cmdline window from CmdWinEnter

Problem:    Cannot close the cmdline window from CmdWinEnter. (George Brown)
Solution:   Reset cmdwin_result earlier. (Christian Brabandt, closes vim/vim#4980)
23324a0b35

src/nvim/ex_getln.c

@@ -6471,12 +6471,15 @@ static int open_cmdwin(void)
   // Save the command line info, can be used recursively.
   save_cmdline(&save_ccline);
 
-  /* No Ex mode here! */
+  // No Ex mode here!
   exmode_active = 0;
 
   State = NORMAL;
   setmouse();
 
+  // Reset here so it can be set by a CmdWinEnter autocommand.
+  cmdwin_result = 0;
+
   // Trigger CmdwinEnter autocommands.
   typestr[0] = (char_u)cmdwin_type;
   typestr[1] = NUL;
@@ -6492,7 +6495,6 @@ static int open_cmdwin(void)
   /*
    * Call the main loop until <CR> or CTRL-C is typed.
    */
-  cmdwin_result = 0;
   normal_enter(true, false);
 
   RedrawingDisabled = i;