Windows: Do not EEXIST exact match during rename

Windows: Do not EEXIST exact match during rename

AFS Rename operations on the file server will delete a
target file if it exists.  Do not prevent renames because
an exact match of the target name exists in the target
directory.

Reviewed-on: http://gerrit.openafs.org/5731
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
(cherry picked from commit 9cf7a628c2ff178b2fa236d2c0a41ca9be315036)

Change-Id: I02c32fab18053e1a37811089812f402d351a6666
Reviewed-on: http://gerrit.openafs.org/6040
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>