This is to make sure this check is called even when building as part of LLVM runtimes when we are doing standalone but not out of tree build. Differential Revision: https://reviews.llvm.org/D28392 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@291592 91177308-0d34-0410-b5e6-96231b3b80d8