[libFuzzer] best effort support for -fsanitize-coverage=trace-pc instrumentation. It is less efficient and precise than -fsanitize-coverage=trace-pc-guard, but still works

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299046 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed