SERVER-13507 increased stability of stepdown_wrt_electable.js by altering its use of parallel shells
SERVER-13470 Give Status move semantics in C++11 mode
SERVER-12255 Be explicit about target micro-architecture for 32-bit x86 builds
SERVER-12255 Fix missing symbols when building a 32 bit tcmalloc
SERVER-12255 Use tcmalloc on 32-bit linux and darwin as well