Move throw out of include headers

include/yaml-cpp/node/detail/impl.h

@@ -14,7 +14,9 @@
 #include <type_traits>
 
 namespace YAML {
-[[noreturn]] void throw_bad_subscript(const YAML::Mark& mark);
+[[noreturn]] extern void throw_bad_subscript(const YAML::Mark& mark);
+[[noreturn]] extern void throw_bad_insert();
+
 namespace detail {
 template <typename Key, typename Enable = void>
 struct get_idx {
@@ -201,8 +203,6 @@ inline bool node_data::remove(const Key& key, shared_memory_holder pMemory) {
   return false;
 }
 
-[[nodiscard]] void throw_bad_insert();
-
 // map
 template <typename Key, typename Value>
 inline void node_data::force_insert(const Key& key, const Value& value,