Tweaks to memory orderings for seg_queue
Tweaks to memory orderings for seg_queue

steveklabnik/crossbeam,crossbeam-rs/crossbeam,phil-opp/crossbeam,Ticki/crossbeam,crossbeam-rs/crossbeam,ticki/baguette,crossbeam-rs/crossbeam,crossbeam-rs/crossbeam,msullivan/crossbeam,schets/crossbeam,huonw/crossbeam,aturon/crossbeam