Windows: Protect ObjectRefCnts with ObjectInfoLock

Windows: Protect ObjectRefCnts with ObjectInfoLock

The ObjectInfoCB.ObjectReferenceCount is tested to determined
when it is safe to remove an FCB from the ObjectInfoCB.  The
value must not be permitted to change while a removal is performed.

Protect AFSRemoveFcb() calls with exclusive holds of the
ObjectInfoCB.NonPagedInfo->ObjectInfoLock.  New functions:

  AFSObjectInfoIncrement()
  AFSObjectInfoDecrement()

perform all increments and decrements while holding the
ObjectInfoLock in a Shared state.

Change-Id: If89b7668ef0a891d55b039d9516620b581c79e10
Reviewed-on: http://gerrit.openafs.org/8224
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Rod Widdowson <rdw@steadingsoftware.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>