Revert "Move internal usages of `alignof`/`__alignof` to use `_LIBCPP_ALIGNOF`. "

This reverts commit 087f065cb0c7463f521a62599884493aaee2ea12.

The tests were failing on 32 bit builds, and I don't have time
to clean them up right now. I'll recommit tomorrow with fixed tests.

llvm-svn: 347816
diff --git a/libcxx/include/__sso_allocator b/libcxx/include/__sso_allocator
index 8aca049..e16b680 100644
--- a/libcxx/include/__sso_allocator
+++ b/libcxx/include/__sso_allocator
@@ -55,14 +55,14 @@
             __allocated_ = true;
             return (pointer)&buf_;
         }
-        return static_cast<pointer>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
+        return static_cast<pointer>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), __alignof(_Tp)));
     }
     _LIBCPP_INLINE_VISIBILITY void deallocate(pointer __p, size_type __n)
     {
         if (__p == (pointer)&buf_)
             __allocated_ = false;
         else
-            _VSTD::__libcpp_deallocate(__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
+            _VSTD::__libcpp_deallocate(__p, __n * sizeof(_Tp), __alignof(_Tp));
     }
     _LIBCPP_INLINE_VISIBILITY size_type max_size() const throw() {return size_type(~0) / sizeof(_Tp);}