CVE-2013-4476: s4:libtls: check for safe permissions of tls private key file (key...

CVE-2013-4476: s4:libtls: check for safe permissions of tls private key file (key.pem)

If the tls key is not owned by root or has not mode 0600 samba will not
start up.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=10234

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Signed-off-by: Björn Baumbach <bb@sernet.de>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Autobuild-User(master): Karolin Seeger <kseeger@samba.org>
Autobuild-Date(master): Mon Nov 11 13:07:16 CET 2013 on sn-devel-104