[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: I81813a500a1651672862c6311c35ccc0a55ce775
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2186633Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67656}

src/utils/ostreams.h

@@ -35,7 +35,7 @@ class V8_EXPORT_PRIVATE OFStreamBase : public std::streambuf {
 class V8_EXPORT_PRIVATE DbgStreamBuf : public std::streambuf {
  public:
   DbgStreamBuf();
-  ~DbgStreamBuf();
+  ~DbgStreamBuf() override;
 
  private:
   int sync() override;
@@ -47,7 +47,7 @@ class V8_EXPORT_PRIVATE DbgStreamBuf : public std::streambuf {
 class DbgStdoutStream : public std::ostream {
  public:
   DbgStdoutStream();
-  ~DbgStdoutStream() = default;
+  ~DbgStdoutStream() override = default;
 
  private:
   DbgStreamBuf streambuf_;