AtomicOrLocked: use std::conditional_t and std::is_trivially_copyable_v

std::conditional_t was added in C++14, is_trivially_copyable_v in C++17, both
do the same as the previous implementation and are a bit more compact.

lib/base/atomic.hpp

@@ -109,7 +109,7 @@ private:
  * @ingroup base
  */
 template <typename T>
-using AtomicOrLocked = typename std::conditional<std::is_trivially_copyable<T>::value, std::atomic<T>, Locked<T>>::type;
+using AtomicOrLocked = std::conditional_t<std::is_trivially_copyable_v<T>, std::atomic<T>, Locked<T>>;
 
 }