[libFuzzer] DFT: when dumping coverage, also dump the total number of instrumented blocks in a function; update merge_data_flow.py to merge coverage

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk/lib/fuzzer@360272 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed