zx_clock_get() signature is being replaced to report errors.
As part of a soft transition, zx_clock_get_new() is introduced with
the final function signature.

Bug: chromium:963956
Change-Id: Ia6d0f4fc560bd9149683011099b064540b54edd6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1616545
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61591}