Fix PR26961 - Add default constructor to std::pointer_safety struct.

In ABI v1 libc++ implements std::pointer_safety as a class type instead
of an enumeration. However this class type does not provide
a default constructor as it should. This patch adds that default constructor.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@291059 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed