Fix test that changed in #59.

The lhs of that comparison got lost, but just adding it back looks
strange:

  sizeof(T1) ==
      ((sizeof(T1) + alignof(T1) - 1) / alignof(T1)) * alignof(T1)

This is equivalent to alignof(T1) < sizeof(T1), which doesn't seem
like a useful thing to check.  Instead, replace the original
`sizeof(T1) == 32` with `sizeof(T1) == 16 + alignof(T1)` instead.

Change-Id: I6a58b2614ce1e7856d439d820f7f197386730cd3