Revert "Preprocessor: Add __ALIGNOF_MAX_ALIGN_T__"

This commit reverts r201037, it's functionality is not needed given the
definition of std::max_align_t in libcxx circa r201843.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202667 91177308-0d34-0410-b5e6-96231b3b80d8