[libFuzzer] Update documentation regarding MSan.

Summary: -fsanitize=fuzzer,memory now works out-of-the-box.

Reviewers: kcc

Reviewed By: kcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49441

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337476 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed