[test] Make RCS test time atomic to fix TSAN

Change-Id: Ibc256e202a75f7dbcba27dad2b591cf45738b005
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3571900
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79809}

test/unittests/logging/runtime-call-stats-unittest.cc

@@ -4,6 +4,8 @@
 
 #include "src/logging/runtime-call-stats.h"
 
+#include <atomic>
+
 #include "include/v8-template.h"
 #include "src/api/api-inl.h"
 #include "src/base/atomic-utils.h"
@@ -21,7 +23,8 @@ namespace internal {
 
 namespace {
 
-static base::TimeTicks runtime_call_stats_test_time_ = base::TimeTicks();
+static std::atomic<base::TimeTicks> runtime_call_stats_test_time_ =
+    base::TimeTicks();
 // Time source used for the RuntimeCallTimer during tests. We cannot rely on
 // the native timer since it's too unpredictable on the build bots.
 static base::TimeTicks RuntimeCallStatsTestNow() {