Summary: Add a Dockerfile for clang-proto-fuzzer

Reviewers: morehouse, vitalybuka

Reviewed By: morehouse

Subscribers: hintonda, cfe-commits

Differential Revision: https://reviews.llvm.org/D36635

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@310774 91177308-0d34-0410-b5e6-96231b3b80d8