Make meta.trans.other/aligned_storage.pass.cpp pass on arm.

The maximum alignment on arm is 8, not 16 like on x86. Use alignof(max_align_t)
to make the test work in both cases.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@210195 91177308-0d34-0410-b5e6-96231b3b80d8