use completion setter object in mp linger mode

mp linger mode was not properly setting the completion status,
as sp does. This caused mp end of scenario saves not to end up
in linger mode when they are reloaded.

src/playmp_controller.cpp

@@ -342,7 +342,7 @@ void playmp_controller::linger()
 
 	// this is actually for after linger mode is over -- we don't want to
 	// stay stuck in linger state when the *next* scenario is over.
-	gamestate_.classification().completion = "running";
+	set_completion setter(gamestate_,"running");
 	// End all unit moves
 	BOOST_FOREACH(unit &u, units_) {
 		u.set_user_end_turn(true);

src/playsingle_controller.cpp

@@ -803,20 +803,6 @@ void playsingle_controller::play_human_turn() {
 		gui_->draw();
 	}
 }
-struct set_completion
-{
-	set_completion(game_state& state, const std::string& completion) :
-		state_(state), completion_(completion)
-	{
-	}
-	~set_completion()
-	{
-		state_.classification().completion = completion_;
-	}
-	private:
-	game_state& state_;
-	const std::string completion_;
-};
 
 void playsingle_controller::linger()
 {

src/playsingle_controller.hpp

@@ -20,6 +20,21 @@
 #include "playturn_network_adapter.hpp"
 #include "replay.hpp"
 
+struct set_completion
+{
+	set_completion(game_state& state, const std::string& completion) :
+		state_(state), completion_(completion)
+	{
+	}
+	~set_completion()
+	{
+		state_.classification().completion = completion_;
+	}
+	private:
+	game_state& state_;
+	const std::string completion_;
+};
+
 class playsingle_controller : public play_controller
 {
 public: