Windows: separate parsemode from fs into own file

Windows: separate parsemode from fs into own file

Separate parsemode() from fs.c into parsemode.c.

Restructure the function prototypes and the fs.h header
to permit building fs.exe from multiple source files.

Reviewed-on: http://gerrit.openafs.org/3591
Reviewed-by: Russ Allbery <rra@stanford.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
(cherry picked from commit 683747b9c4b3d9d77fb8c68df09a59807d027a42)

Change-Id: I3ed5f647631bdd6983a53f4e6a2193aaddf37e0f
Reviewed-on: http://gerrit.openafs.org/3805
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>