ffs() vs findFirstSet() are slightly different, indexing is 0-based instead of 1-based. Example mingw error: http://build.chromium.org/p/tryserver.nacl/builders/nacl-toolchain-win7-pnacl-x86_64/builds/1920/steps/llvm_i686_w64_mingw32%20%28build%29/logs/stdio BUG=none R=stichnot@chromium.org Review URL: https://codereview.chromium.org/563303002
