Windows: AFSSetDispositionInfo Verify Dir Enum

Before testing whether or not a directory is empty, the directory
must be enumerated.  If it is not, enumerate it.

Change-Id: I0302733821e1d5c6be3198be7fe75333d8e01245
Reviewed-on: http://gerrit.openafs.org/9780
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>