Correct GCC vector workaround for trivially-copyable types

Fixes #58

tl/expected.hpp

@@ -84,7 +84,7 @@ namespace tl {
 #ifdef _GLIBCXX_VECTOR
       template<class T, class A>
       struct is_trivially_copy_constructible<std::vector<T,A>>
-          : std::is_trivially_copy_constructible<T>{};
+          : std::false_type{};
 #endif
   }
 }