This reverts commit r312890 because the test case fails to compile for
older versions of Clang that reject initializing a const object without
a user defined constructor.
Since this patch should go into 5.0.1, I want to keep it an atomic change,
and will re-commit it with a fixed test case.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@312891 91177308-0d34-0410-b5e6-96231b3b80d8