Enable partial C++11 support in ancient g++

Change-Id: Ie80586f037350d416ead25c190225a47c564b37e
Reviewed-on: http://review.couchbase.org/40903
Reviewed-by: Dave Rigby <daver@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>