Add usleep for win32

Change-Id: I766f77a81fae5fa5853f5be38f4d792d3f910d3a
Reviewed-on: http://review.couchbase.org/31209
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>