Windows: remove unused and leaked uniRootFileNameClone

In AFSCommonCreate remove the allocated but never used but leaked
'uniRootFileNameClone' Unicode string.

Reviewed-on: http://gerrit.openafs.org/9920
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit f4b78c3eb12afc70d5ff3021313d3f868cb9f661)

Change-Id: Ife8b429cb1240517def38ea44a9e3daa00e83ee8
Reviewed-on: http://gerrit.openafs.org/9921
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>