This is a revert of r347421, except I'm using the with_system_cxx_lib lit feature instead of availability to mark the test as unsupported (because the problem is a bug in the dylib itself). In r347421, I said I wasn't able to reproduce the issue and that's why I was removing it: this was because I ran lit slightly wrong. The problem mentioned really exists. git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@347475 91177308-0d34-0410-b5e6-96231b3b80d8