Windows: use spin counts for osi base locks

Windows: use spin counts for osi base locks

On multiprocessor systems, spin counts are faster than entering
a processor wait state when there is critical section contention.
Microsoft recommends a count of 4000.  This feature is only available
on XP and above which is fine since OpenAFS master and 1.7 no longer
support Windows 2000.

Change-Id: I1b40d00b2a91e60e1676a53e1c38eb5f9bfadc69
Reviewed-on: http://gerrit.openafs.org/7719
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>