[compiler-rt] Fix the Asan unittest on Windows

Summary:
The build bot is broken because the runtime library doesn't have
debug information.

This is broken due to a recent change:
  http://reviews.llvm.org/D21554

Reviewers: rnk

Subscribers: kubabrecka, llvm-commits, chrisha

Differential Revision: http://reviews.llvm.org/D21862

llvm-svn: 274172