gtest: fix std::is_trivially_copy_constructible for gcc 4.8

error:
```
/fmt/test/gtest/gtest.h: In static member function 'static constexpr bool testing::internal::MatcherBase<T>::IsInlined()':
/fmt/test/gtest/gtest.h:6512:12: error: 'is_trivially_copy_constructible' was not declared in this scope
            std::is_trivially_copy_constructible<M>::value &&
            ^
/fmt/test/gtest/gtest.h:6512:45: error: expected primary-expression before '>' token
            std::is_trivially_copy_constructible<M>::value &&
                                             ^
/fmt/test/gtest/gtest.h:6512:46: error: '::value' has not been declared
            std::is_trivially_copy_constructible<M>::value &&
```

test/gtest/gtest.h

@@ -6272,6 +6272,14 @@ class MatcherInterface : public MatcherDescriberInterface {
 
 namespace internal {
 
+#if defined(__GNUC__) && !defined(__clang__) && __GNUC__ < 5
+template<typename T>
+using is_trivially_copy_constructible = std::has_trivial_copy_constructor<T>;
+#else
+template<typename T>
+using is_trivially_copy_constructible = std::is_trivially_copy_constructible<T>;
+#endif
+
 struct AnyEq {
   template <typename A, typename B>
   bool operator()(const A& a, const B& b) const { return a == b; }
@@ -6509,7 +6517,7 @@ class MatcherBase : private MatcherDescriberInterface {
   template <typename M>
   static constexpr bool IsInlined() {
     return sizeof(M) <= sizeof(Buffer) && alignof(M) <= alignof(Buffer) &&
-           std::is_trivially_copy_constructible<M>::value &&
+           is_trivially_copy_constructible<M>::value &&
            std::is_trivially_destructible<M>::value;
   }