Windows: buf_usedCount can be 64-bit
If buf_usedCount is 64-bit, must use 64-bit Interlocked operations.
Define buf_IncrementUsedCount() and buf_DecrementUsedCount() macros
to wrap the 32-bit and 64-bit Interlocked operations as appropriate.
Change-Id: Icbcb4d20530cc33b43e3c58c3ce74251b12c1e93
Reviewed-on: http://gerrit.openafs.org/8729
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Jeffrey Altman <jaltman@your-file-system.com>