Ignore SIGUSR1/SIGHUP during exit notification

Ignore SIGUSR1/SIGHUP during exit notification

This allows exit notification to complete and finally trigger SIGTERM.
The current practice of allowing a restart in this state clears
the exit notification timer data and thus loses the SIGTERM.

Trac #687

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1465274660-11009-2-git-send-email-selva.nair@gmail.com>
URL: http://article.gmane.org/gmane.network.openvpn.devel/11814
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 63b3e000c9141f4ca03a374354da26334257bc18)