Fixed template-class definitions in fx-sig.cpp

Fortune for libfx-sync's current commit: Small blessing − 小吉

src/fx-sig.cpp

@@ -130,14 +130,14 @@ namespace fx::signal {
 #define IMPL_SPEC // 
 	
 #define IMPL_CLASS thread_wait_for_signals
-	extern template class $class< void(*)(int) >;
-	extern template class $class< void(*)(int, std::stop_token) >;
+	template class $class< void(*)(int) >;
+	template class $class< void(*)(int, std::stop_token) >;
 
-	extern template class $class<std::function<void(int)> >;
-	extern template class $class<std::move_only_function<void(int)> >;
+	template class $class<std::function<void(int)> >;
+	template class $class<std::move_only_function<void(int)> >;
 
-	extern template class $class<std::function<void(int, std::stop_token)> >;
-	extern template class $class<std::move_only_function<void(int, std::stop_token)> >;
+	template class $class<std::function<void(int, std::stop_token)> >;
+	template class $class<std::move_only_function<void(int, std::stop_token)> >;
 #undef IMPL_CLASS /* thread_wait_for_signals */
 
 }