Make DebugInfo::flags access relaxed atomic

Bug: v8:11576
Change-Id: I3e15a3311eae44b0d70bcc8dc536eb777d92151f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2835730
Auto-Submit: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74118}

src/objects/debug-objects.tq

@@ -51,7 +51,7 @@ extern class DebugInfo extends Struct {
   // Fixed array holding status information for each active break point.
   break_points: FixedArray;
   // A bitfield that lists uses of the current instance.
-  flags: SmiTagged<DebugInfoFlags>;
+  @relaxedRead @relaxedWrite flags: SmiTagged<DebugInfoFlags>;
   coverage_info: CoverageInfo|Undefined;
 }