Summary:
I copied the sanitizer-related logic in libcxx/lib/CMakeLists.txt. In
the future, it would be great to avoid duplicating this logic in the
compiler, libc++ and libc++abi.
Reviewers: EricWF
Subscribers: mgorny, christof, dexonsmith, libcxx-commits, davide
Differential Revision: https://reviews.llvm.org/D53028
llvm-svn: 344191