OpenBSD UBsan support final missing bits

Summary:
One forgotten file change + reordering one header due to clang-format

Patch by David CARLIER

Reviewers: vitalybuka, vsk

Subscribers: kubamracek, fedor.sergeev, llvm-commits, #sanitizers

Differential Revision: https://reviews.llvm.org/D44556

llvm-svn: 327758