Kill FOLLY_ALIGNED etc

Kill FOLLY_ALIGNED etc

Summary:
[Folly] Kill `FOLLY_ALIGNED` etc.

`alignas` is standardized as of C++11. Let us just use that.

Replace:
* `FOLLY_ALIGNED` with `alignas`
* `FOLLY_ALIGNED_MAX` with `alignas(folly::max_align_v)`
* `FOLLY_ALIGN_TO_AVOID_FALSE_SHARING` with `alignas(folly::hardware_destructive_interference_size)`

Because where `alignas` may be placed is more restrictive than where attributes may be placed, we also need to move these directives in some cases on top of doing the replacement.

Reviewed By: Orvid

Differential Revision: D6555167

fbshipit-source-id: 4b05b570bace3f8c0fe810b6dd58781dd45757f4