Windows: no drive subst for NPCancelConnection

Windows: no drive subst for NPCancelConnection

NPCancelConnection() must use the results of a Get Connection
ioctl to the afs redirector and not the result of Drive Letter
Substitution queries via DosQueryDevice().  Rename NPGetConnection()
to NPGetConnectionCommon() and add a new parameter to indicate
whether drive substitution is ok.

Change-Id: I42cd4488038f128ae90356a41bc538966d9cebed
Reviewed-on: http://gerrit.openafs.org/6139
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>