vim-patch:8.1.2044: no easy way to process postponed work

Problem:    No easy way to process postponed work. (Paul Jolly)
Solution:   Add the SafeState autocommand event.

8aeec40207

Co-authored-by: Bram Moolenaar <Bram@vim.org>

src/nvim/ex_getln.c

@@ -943,6 +943,8 @@ theend:
 
 static int command_line_check(VimState *state)
 {
+  CommandLineState *s = (CommandLineState *)state;
+
   redir_off = true;        // Don't redirect the typed command.
   // Repeated, because a ":redir" inside
   // completion may switch it on.
@@ -952,6 +954,9 @@ static int command_line_check(VimState *state)
                            // that occurs while typing a command should
                            // cause the command not to be executed.
 
+  // Trigger SafeState if nothing is pending.
+  may_trigger_safestate(s->xpc.xp_numfiles <= 0);
+
   cursorcmd();             // set the cursor on the right spot
   ui_cursor_shape();
   return 1;