printing: reload printer shares on OpenPrinter

printing: reload printer shares on OpenPrinter

The printer share inventory should be reloaded on open _and_
enumeration, as there are some clients, such as cupsaddsmb, that do not
perform an enumeration prior to access.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=10652

Signed-off-by: David Disseldorp <ddiss@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
Autobuild-User(master): Andreas Schneider <asn@cryptomilk.org>
Autobuild-Date(master): Fri Aug  8 16:33:50 CEST 2014 on sn-devel-104