Add Travis CI config for 32-bit gcc builds.
Add Travis CI config for 32-bit gcc builds.

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