patch 8.1.2046: SafeState may be triggered at the wrong moment

Problem:    SafeState may be triggered at the wrong moment.
Solution:   Move it up higher to after where messages are processed.  Add a
            SafeStateAgain event to tigger there.

src/autocmd.c

@@ -156,6 +156,7 @@ static struct event_name
     {"QuitPre",		EVENT_QUITPRE},
     {"RemoteReply",	EVENT_REMOTEREPLY},
     {"SafeState",	EVENT_SAFESTATE},
+    {"SafeStateAgain",	EVENT_SAFESTATEAGAIN},
     {"SessionLoadPost",	EVENT_SESSIONLOADPOST},
     {"ShellCmdPost",	EVENT_SHELLCMDPOST},
     {"ShellFilterPost",	EVENT_SHELLFILTERPOST},