Windows: more warnings on kernel builds

Windows: more warnings on kernel builds

This is the same sort of changes a per git commit 8a4094e9ffa5d0f96501817c8ffd3cc8dc7ec62b
but this time for the fs tree.  Again most of the work is UNREFERENCED_PARAMETER, initialize
variables where the compiler lacks the smarts and remove unused locals.

Change-Id: Id67246e8aaee292cb6f02833e9960f9545c55101
Reviewed-on: http://gerrit.openafs.org/8823
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>