Enable assertions in both stages.
Release+Asserts is fast enough.
No need to let insanity through.

Patch By: mcgrathr

Reviewers: phosek

Reviewed By: phosek

Differential Revision: https://reviews.llvm.org/D41471

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@321316 91177308-0d34-0410-b5e6-96231b3b80d8