Fix data race in leak detection

TSAN identified a data race between updates to the states_ map (ex. in Mock::UnregisterLocked) and the iteration done in this destructor. Writes to the map use g_gmock_mutex, but the destructor does not acquire it. Acquiring the lock here fixes the data race.

It should only be possible to trigger this TSAN finding in cases where a mock object is deleted by a thread other than the main thread.

PiperOrigin-RevId: 591935393
Change-Id: I9dd1faa40058d78e165a91333346514b4b73365c

googlemock/src/gmock-spec-builders.cc

@@ -490,6 +490,7 @@ class MockObjectRegistry {
   // failure, unless the user explicitly asked us to ignore it.
   ~MockObjectRegistry() {
     if (!GMOCK_FLAG_GET(catch_leaked_mocks)) return;
+    internal::MutexLock l(&internal::g_gmock_mutex);
 
     int leaked_count = 0;
     for (StateMap::const_iterator it = states_.begin(); it != states_.end();