[libFuzzer] add DeepRecursionTest, inspired by https://guidovranken.wordpress.com/2017/07/08/libfuzzer-gv-new-techniques-for-dramatically-faster-fuzzing/ (Stack-depth-guided fuzzing). libFuzzer does not solve it yet.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@308571 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed