Mask general purpose signals for notifyd.

Mask general purpose signals for notifyd.

Currently there is no signal handling available for notify daemon.
Signals like SIGHUP and SIGUSR1 can lead to terminate the notify
daemon. Masking these signals for notifyd as we are not handling them.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11840

Signed-off-by: Hemanth Thummala <hemanth.thummala@nutanix.com>
Reviewed-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Fri Apr 15 15:31:19 CEST 2016 on sn-devel-144

(cherry picked from commit cade673f5fff8a578b8620149688ecc93e981205)