Use '=default' to define trivial constructor/destructors

https://clang.llvm.org/extra/clang-tidy/checks/modernize/use-equals-default.html

PiperOrigin-RevId: 526079054
Change-Id: Ia4db21e3e5f58b90de05d52fd94b291ed06d785d

googlemock/test/gmock_leak_test_.cc

@@ -40,13 +40,13 @@ using ::testing::Return;
 
 class FooInterface {
  public:
-  virtual ~FooInterface() {}
+  virtual ~FooInterface() = default;
   virtual void DoThis() = 0;
 };
 
 class MockFoo : public FooInterface {
  public:
-  MockFoo() {}
+  MockFoo() = default;
 
   MOCK_METHOD0(DoThis, void());