Fix build break on WIN32

New versions of MSVC have stdint.h

Change-Id: Ica591b67c9e09541648d3a47e6c8fc98afde2547
Reviewed-on: http://review.couchbase.org/42716
Tested-by: Trond Norbye <trond.norbye@gmail.com>
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>