Windows: permit clean when switching platforms

Windows: permit clean when switching platforms

When switching between i386 and amd64 in the same build tree
the "clean" make directive would fail due to NTLang.bat not
having been built in the new platform's destination directory.
Force NTLang.bat to be built as a dependency of cleanup and
delete it at the end along with the version files.

Reviewed-on: http://gerrit.openafs.org/3615
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
(cherry picked from commit 605b7c3baaeb7553cb2e150f1156eba6be04c1f8)

Change-Id: Ia215c34f06976dee588292fccb7396a49ab98035
Reviewed-on: http://gerrit.openafs.org/3813
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>