[libFuzzer] exit without running atexit handlers in libfuzzer's crash handler

Summary:
It's not safe to assume that atexit handlers can be run once the app crashed.

Patch by Jochen Eisinger.

Reviewers: kcc, vitalybuka

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D32640

git-svn-id: svn://svn.chromium.org/llvm-project/llvm/trunk/lib/Fuzzer@302076 0b72dbe1-c17f-4bc7-b9db-2b4152be0356
1 file changed