s3: winbindd: On new client connect, prune idle or hung connections older than "winbi...

s3: winbindd: On new client connect, prune idle or hung connections older than "winbind request timeout"

Bug 3204 winbindd: Exceeding 200 client connections, no idle connection found

https://bugzilla.samba.org/show_bug.cgi?id=3204

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ira Cooper <ira@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Tue Jul 29 23:31:14 CEST 2014 on sn-devel-104

(cherry picked from commit f9588675ea3cb2f1fabd07a4ea8b2138d65aee83)

Autobuild-User(v4-1-test): Karolin Seeger <kseeger@samba.org>
Autobuild-Date(v4-1-test): Mon Sep  1 23:46:50 CEST 2014 on sn-devel-104