[libcxx] Allow sanitizing libcxx with ASan+UBSan simultaneously

Allow building with LLVM_USE_SANITIZER=“Address;Undefined” (and “Undefined;Address”).

Differential Revision: https://reviews.llvm.org/D24569



git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@281603 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed