Reads from the compiler thread require either 1. the last write to
happen before the compiler thread starts, or 2. acquire-release
semantics. For simplicity, this CL converts all NativeContext field
writes to be acq-rel. With the usual exception of writes from
generated code (these are limited for NativeContexts though).

The situation of context sets/gets is still somewhat complex:

- Context::get/set are relaxed (but don't use the corresponding tag)
- Context::get(.., kAcquireLoad) and Context::set(.., kReleaseStore)
  are acquire-release.
- Context::set_foo (defined for all native context fields) uses
  kReleaseStore underneath.
- Context::get_foo (defined for all native context fields) uses
  the default relaxed getter. The get_foo(kAcquireLoad) variant uses
  the acquire getter.
- NativeContext hides the default relaxed setter since all
  NativeContext sets should be acq-rel.

Ideally (future work), this should be simplified and made more explicit.
For example, get/set_foo could move to the NativeContext class, and we
could reevaluate whether we really need both relaxed and acq-rel
semantics (the pairing non-atomic/acq-rel feels more natural lets
tsan find concurrency issues).

Bug: v8:7790
Change-Id: I25efd37ece758da5a11dc11c6ae913e4975f4d20
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2891575Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74524}