s4:lib/messaging: use 'msg.lock' and 'msg.sock' for messaging related subdirs

s4:lib/messaging: use 'msg.lock' and 'msg.sock' for messaging related subdirs

In Samba 4.2, we used lock_path("msg") (with 0700) for the socket directory,
while we use lock_path("msg") (with 0755) for the lock file directory.

This generates a conflict that prevents samba, smbd, nmbd and winbindd
from starting after an upgrade.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11515

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
Autobuild-User(master): Stefan Metzmacher <metze@samba.org>
Autobuild-Date(master): Thu Sep 17 09:04:59 CEST 2015 on sn-devel-104