Windows: *ParseIoctlPath path has trailing slash

Windows: *ParseIoctlPath path has trailing slash

Make it explicit that a pioctl input path that ends in a trailing
slash is consistently interpretted as a directory.

  \\afs\cell\mp\dir\  == \\afs\cell\mp\dir\.

Change-Id: Id55638157cd69297d1a072ae04f94b968ea03b30
Reviewed-on: http://gerrit.openafs.org/8755
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>