backout last change and define atomic_xxx to just use Mach's hardware RMW cycles for both Panther and Tiger
backout last change and define atomic_xxx to just use Mach's hardware
RMW cycles for both Panther and Tiger

TopPano/sctp-refimpl,timsuchanek/sctp-refimpl,sdd330/sctp-refimpl,sdd330/sctp-refimpl,ossy-szeged/sctp-refimpl,TopPano/sctp-refimpl,ossy-szeged/sctp-refimpl,TopPano/sctp-refimpl,TopPano/sctp-refimpl,timsuchanek/sctp-refimpl,TopPano/sctp-refimpl,deepak899/sctp-refimpl,sdd330/sctp-refimpl,deepak899/sctp-refimpl,sctplab/sctp-refimpl,sctplab/sctp-refimpl,gale320/sctp-refimpl,ossy-szeged/sctp-refimpl,tosakanth/sctp-refimpl,sdd330/sctp-refimpl,tosakanth/sctp-refimpl,timsuchanek/sctp-refimpl,TopPano/sctp-refimpl,ossy-szeged/sctp-refimpl,xwhuang/sctp-refimpl,ossy-szeged/sctp-refimpl,sctplab/sctp-refimpl,gale320/sctp-refimpl,tosakanth/sctp-refimpl,deepak899/sctp-refimpl,sctplab/sctp-refimpl,ossy-szeged/sctp-refimpl,timsuchanek/sctp-refimpl,timsuchanek/sctp-refimpl,xwhuang/sctp-refimpl,ossy-szeged/sctp-refimpl,TopPano/sctp-refimpl,xwhuang/sctp-refimpl,ossy-szeged/sctp-refimpl,sdd330/sctp-refimpl,deepak899/sctp-refimpl,gale320/sctp-refimpl,tosakanth/sctp-refimpl,sdd330/sctp-refimpl,TopPano/sctp-refimpl,tosakanth/sctp-refimpl,gale320/sctp-refimpl,gale320/sctp-refimpl,deepak899/sctp-refimpl,tosakanth/sctp-refimpl,timsuchanek/sctp-refimpl,xwhuang/sctp-refimpl,sdd330/sctp-refimpl,sdd330/sctp-refimpl,xwhuang/sctp-refimpl,gale320/sctp-refimpl,sctplab/sctp-refimpl,ossy-szeged/sctp-refimpl,tosakanth/sctp-refimpl,TopPano/sctp-refimpl,timsuchanek/sctp-refimpl,gale320/sctp-refimpl,gale320/sctp-refimpl,timsuchanek/sctp-refimpl,timsuchanek/sctp-refimpl,sctplab/sctp-refimpl,sdd330/sctp-refimpl,xwhuang/sctp-refimpl,tosakanth/sctp-refimpl,gale320/sctp-refimpl,tosakanth/sctp-refimpl,deepak899/sctp-refimpl