- std::memory_order is no longer an enum, remove the double
  qualification. P0439R0.
- `icu::StringPiece(nullptr, 0)` is now ambiguous due to char8_t no
  longer being equal to char. Use the default constructor. P0482R6.
- WasmGlobal is aggregate initialized, remove the default ctor. It's
  move-only anyways because some of its members are. P1008R1.
- Remove stray `inline` keyword Clang warns about.

Change-Id: I63dca25350a4e560779dc637c3bf637a385dd0c8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3472497
Auto-Submit: Benjamin Kramer <kramerb@google.com>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79230}