Windows: Freelance get callback sync and uninitialized variables

Windows: Freelance get callback sync and uninitialized variables

In cm_GetCallback the Freelance mode case did not properly
synchronize attempts to fake obtain a callback.

cm_GetCallback also failed to initialize the contents of afsStatus and
volSync which are used as input to cm_MergeStatus.
cm_MergeStatus special cased the freelance root.afs volume root
directory but failed to handle any other freelance volume objects.
As a result it used the contents of the uninitialzed input structures
to populate the status of the object for which the callback was
obtained.

LICENSE MIT

Reviewed-on: http://gerrit.openafs.org/401
Tested-by: Asanka Herath <asanka@secure-endpoints.com>
Reviewed-by: Asanka Herath <asanka@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>