Reverted r199330 and r199331.
We cannot unconditionally require libc++ for all platforms. Some builders build with gcc, some want libstdc++, and such (see http://lab.llvm.org:8011/builders/clang-mergefunc-x86_64-freeBSD9.2/builds/2253 for instance). Please consider defining extra_configure_args for particular builders instead or do this specifically for darwin.


git-svn-id: https://llvm.org/svn/llvm-project/zorg/trunk@199792 91177308-0d34-0410-b5e6-96231b3b80d8