Fixup some missing overrides in googletest.

This CL adds a couple missing overrides in the googletest sources.
These were found downstream when -Wsuggest-override and
-Wsuggest-destructor-override were enabled.

PiperOrigin-RevId: 447754883
Change-Id: I7bf35a8757cbc5ae157827037aa3d13f47392406

Author: Abseil Team

googletest/include/gtest/internal/gtest-port.h

@@ -1530,7 +1530,7 @@ class ThreadLocal : public ThreadLocalBase {
   explicit ThreadLocal(const T& value)
       : default_factory_(new InstanceValueHolderFactory(value)) {}
 
-  ~ThreadLocal() { ThreadLocalRegistry::OnThreadLocalDestroyed(this); }
+  ~ThreadLocal() override { ThreadLocalRegistry::OnThreadLocalDestroyed(this); }
 
   T* pointer() { return GetOrCreateValue(); }
   const T* pointer() const { return GetOrCreateValue(); }
@@ -1559,7 +1559,7 @@ class ThreadLocal : public ThreadLocalBase {
         ->pointer();
   }
 
-  virtual ThreadLocalValueHolderBase* NewValueForCurrentThread() const {
+  ThreadLocalValueHolderBase* NewValueForCurrentThread() const override {
     return default_factory_->MakeNewHolder();
   }