Revert "Implement LWG 2221 - No formatted output operator for nullptr."

This reverts r342566 as it causes on bots linker errors like

> Undefined symbols for architecture i386:
>   "std::__1::basic_ostream<char, std::__1::char_traits<char> >::operator<<(std::nullptr_t)", referenced from:


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@342599 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed