initial change to use mmap for OS/X
initial change to use mmap for OS/X

abeels/bde,gbleaney/Allocator-Benchmarks,idispatch/bde,dharesign/bde,frutiger/bde,che2/bde,RMGiroux/bde-allocator-benchmarks,osubboo/bde,bloomberg/bde-allocator-benchmarks,apaprocki/bde,che2/bde,mversche/bde,bloomberg/bde-allocator-benchmarks,gbleaney/Allocator-Benchmarks,mversche/bde,abeels/bde,apaprocki/bde,jmptrader/bde,bloomberg/bde,bowlofstew/bde,apaprocki/bde,bloomberg/bde,RMGiroux/bde-allocator-benchmarks,bloomberg/bde,gbleaney/Allocator-Benchmarks,jmptrader/bde,bloomberg/bde-allocator-benchmarks,idispatch/bde,RMGiroux/bde-allocator-benchmarks,dharesign/bde,saxena84/bde,mversche/bde,apaprocki/bde,abeels/bde,che2/bde,osubboo/bde,saxena84/bde,minhlongdo/bde,saxena84/bde,bowlofstew/bde,dharesign/bde,frutiger/bde,dharesign/bde,dbremner/bde,bloomberg/bde,frutiger/bde,mversche/bde,RMGiroux/bde-allocator-benchmarks,apaprocki/bde,bloomberg/bde-allocator-benchmarks,gbleaney/Allocator-Benchmarks,jmptrader/bde,frutiger/bde,abeels/bde,osubboo/bde,dbremner/bde,bowlofstew/bde,idispatch/bde,bowlofstew/bde,che2/bde,dbremner/bde,minhlongdo/bde,dbremner/bde,abeels/bde,saxena84/bde,minhlongdo/bde,jmptrader/bde,minhlongdo/bde,bloomberg/bde,bloomberg/bde-allocator-benchmarks,osubboo/bde,idispatch/bde,abeels/bde,RMGiroux/bde-allocator-benchmarks