Use fsync instead of fdatasync on FreeBSD
Use fsync instead of fdatasync on FreeBSD

Change-Id: I1e94f252b9508480734514c8d8bb5dcfa9e8fb0e
Reviewed-on: http://review.couchbase.org/50774
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>

abhinavdangeti/couchstore,abhinavdangeti/couchstore,abhinavdangeti/couchstore,vmx/couchstore,couchbaselabs/couchstore,couchbaselabs/couchstore,vmx/couchstore,vmx/couchstore,couchbaselabs/couchstore