Currently, all background compile tasks run for 50ms, then they all
publish their results and restart. This results in significant
contention during the publish phase.
This CL introduces an atomic counter on the {CompilationStateImpl} to
distribute the deadline more evenly: Each task executes between 50ms
and 200ms, and tries to pick a deadline 5ms after the previously
assigned deadline, if this lies within these boundaries. This speeds up
publishing significantly and saves several percent compilation time
overall.

R=mstarzinger@chromium.org

Bug: v8:8916
Change-Id: Id32a5a72c1dd44d30df2ea09643b2a6e4f436944
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627984
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61841}