[clang-tidy] Add override to overridden destructors

See
https://clang.llvm.org/extra/clang-tidy/checks/modernize-use-override.html
for more on this warning.

Bug: v8:10488
Change-Id: Ic885590553364db58259ed1d211b3ace4bfe9d23
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2233984Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68298}

src/d8/d8-platforms.cc

@@ -102,7 +102,7 @@ class DelayedTasksPlatform : public Platform {
     DCHECK_NOT_NULL(platform_);
   }
 
-  ~DelayedTasksPlatform() {
+  ~DelayedTasksPlatform() override {
     // When the platform shuts down, all task runners must be freed.
     DCHECK_EQ(0, delayed_task_runners_.size());
   }

src/heap/memory-measurement.cc

@@ -95,7 +95,7 @@ class V8_EXPORT_PRIVATE MeasureMemoryDelegate
  public:
   MeasureMemoryDelegate(Isolate* isolate, Handle<NativeContext> context,
                         Handle<JSPromise> promise, v8::MeasureMemoryMode mode);
-  ~MeasureMemoryDelegate();
+  ~MeasureMemoryDelegate() override;
 
   // v8::MeasureMemoryDelegate overrides:
   bool ShouldMeasure(v8::Local<v8::Context> context) override;

src/objects/intl-objects.cc

@@ -1471,7 +1471,7 @@ class Iterator : public icu::Locale::Iterator {
   Iterator(std::vector<std::string>::const_iterator begin,
            std::vector<std::string>::const_iterator end)
       : iter_(begin), end_(end) {}
-  virtual ~Iterator() = default;
+  ~Iterator() override = default;
 
   UBool hasNext() const override { return iter_ != end_; }