added the -C option to smbtorture

added the -C option to smbtorture

this option takes a filename containing a list of UNC names. When
supplied to a torture test that uses multiple client connections the
test will distribute the load across the listed UNC names. This allows
you to use NBENCH effectively against a server that has multiple IP
addresses, and spread the load among them.
(This used to be commit e0d9502aa20e2e9a343274cd7f12e6ef2f49c104)