add shgrowth benchmark, remove default -flto from build options
add shgrowth benchmark, remove default -flto from build options

bloomberg/bde-allocator-benchmarks,gbleaney/Allocator-Benchmarks,RMGiroux/bde-allocator-benchmarks,gbleaney/Allocator-Benchmarks,gbleaney/Allocator-Benchmarks,RMGiroux/bde-allocator-benchmarks,bloomberg/bde-allocator-benchmarks,RMGiroux/bde-allocator-benchmarks,bloomberg/bde-allocator-benchmarks,bloomberg/bde-allocator-benchmarks,gbleaney/Allocator-Benchmarks,bloomberg/bde-allocator-benchmarks,RMGiroux/bde-allocator-benchmarks,RMGiroux/bde-allocator-benchmarks