[libFuzzer] initial support of -fsanitize-coverage=inline-8bit-counters in libFuzzer. This is not fully functional yet, but simple tests work 

git-svn-id: svn://svn.chromium.org/llvm-project/llvm/trunk/lib/Fuzzer@305331 0b72dbe1-c17f-4bc7-b9db-2b4152be0356
8 files changed