winbindd: disconnect child process if request is cancelled at main process

winbindd: disconnect child process if request is cancelled at main process

When cancelling a request at the main winbindd process, that is currently
being served by a child winbindd process, just freeing all objects related
to the request is not enough, as the next bytes to come through the pipe
from the child process are the response to the cancelled request, and the
object reading those bytes will be the next request. This breaks the protocol.

This change, upon canceling a request that is being served, closes the
connection to the child process, causing the next request to be served
by a new child process (and the detached child to die eventually).

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11358

Signed-off-by: Uri Simchoni <urisimchoni@gmail.com>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
Autobuild-User(master): Andreas Schneider <asn@cryptomilk.org>
Autobuild-Date(master): Mon Jun 29 14:00:24 CEST 2015 on sn-devel-104