MB-9407 extend get_disk_data fix (MB-6540) to OS X Mavericks

and future Darwin versions

Change-Id: Ia4ad0a7658b3a54abae3bad14dec90c10bbd94f0
Reviewed-on: http://review.couchbase.org/30149
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>