This patch does the following:
* Remove <__config> includes from some container tests.
* Guards uses of std::launch::any in async tests because it's an extension.
* Move "test/std/extensions" to "test/libcxx/extensions"
* Moves various non-standard tests including those in "sequences/vector",
"std/localization" and "utilities/meta".
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@267981 91177308-0d34-0410-b5e6-96231b3b80d8
