[cmake] Allow building fuzzers with OSS-Fuzz flags.

Reviewers: kcc, bogner

Reviewed By: bogner

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D38858

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315629 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed