winbind: winbind_messaging_context -> server_messaging_context

winbind: winbind_messaging_context -> server_messaging_context

Don't use winbind_messaging_context anymore.

This fixes a bug analysed by Peter Somogyi <PSOMOGYI@hu.ibm.com>: If a
parent winbind forks, it only called reinit_after_fork on
winbind_messaging_context. On the other hand, deep in dbwrap_open we use
server_messaging_context(). This is not reinitialized by
winbind_reinit_after fork, so the parent and child share a ctdb
connection. This is invalid, because replies from ctdb end up in the
wrong process.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13150

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>