TSan reports errors if one thread changes the ref count using relaxed
semantics, then another thread frees the code object. Acquire-release
semantics fix this, as they impose an ordering between the memory
accesses of different threads.

R=mstarzinger@chromium.org

Bug: v8:8217, v8:9200
Change-Id: I30ce150154e6459c2c64e16be603f29187af1dcd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1594553
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61205}