Windows: add osi_TWaitExt(), fix osi_TWait()

Windows: add osi_TWaitExt(), fix osi_TWait()

osi_TWait() was adding new locks to the turnstile at the tail
which is the end of the queue locks are removed from.  This
implemented LIFO instead of FIFO when FIFO is the "fair" order
to service lock requests.

osi_TWaitExt() is added to permit the Reader to Writer upgrade
request to use LIFO when more than one reader is present.

Change-Id: Ib6435a3edc2cb8519939cfad93e0db4b0604da2d
Reviewed-on: http://gerrit.openafs.org/6435
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>