[libFuzzer] add an experimental flag -experimental_len_control=1 that sets max_len to 1M and tries to increases the actual max sizes of mutations very gradually. Also remove a bit of dead code

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@289998 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed