Added cb_cond_timedwait for win32

Change-Id: Ib86ce1f2d2df6bc0c36606e9c9014c789d440730
Reviewed-on: http://review.couchbase.org/31628
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>