Windows: Remove Fcb.Specific.File.LazyWriterThread

Windows: Remove Fcb.Specific.File.LazyWriterThread

The LazyWriterThread should not be recorded in the FCB.  It is
possible for multiple lazy writes to occur on a file in parallel
in separate threads.  The value is not used for anything in any
case.  AFSCommonWrite() tests the LazyWriterThread value but only
if 'bMapped' is FALSE.  Since 'bMapped' is always TRUE, the
comparison is never performed.   Remove the test and the value.

Change-Id: Iddbb65d2125f39f0362aba72ae20ab2666944367
Reviewed-on: http://gerrit.openafs.org/8241
Tested-by: Rod Widdowson <rdw@steadingsoftware.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>