replace std::aligned_storage

There's no reason to use std::aligned_storage when it's simpler to use
an array and alignas().  This way you don't have to remember whether the
template arguments are size-then-align or align-then-size, you don't
have to remember to use the _t variant or typename ... ::type, and
there's no risk to forgetting the alignment parameter entirely.

It doesn't look like this was deprecated, but I still think this paper
makes good arguments for why we shouldn't use it:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1413r1.pdf

Bug: skia:10921
Change-Id: Ia64a2e43c4cba9b4d64138a7474e353a8eaf01a6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/333258
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
5 files changed