Windows: avoid deadlock if bulk error during enum

Windows: avoid deadlock if bulk error during enum

If the cache manager has a valid callback at the start of a
directory enumeration, the service can begin a bulk status rpc
which can fail.  The error code from the rpc is never propagated
to the caller, therefore the caller loops forever attempting to
complete the enumeration with status info.

Fix it by returning the error.

Change-Id: I53892ddf338152d53c533ef31c3b1047c96bfbf2
Reviewed-on: http://gerrit.openafs.org/6461
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>