- fixed lockup on Shareware screen when quitting Duke

Two errors: the menu wasn’t closed and the shareware check was inverted.

source/core/menu/razemenu.cpp

@@ -216,6 +216,7 @@ CCMD(menu_quit)
 
 	DMenu* newmenu = CreateMessageBoxMenu(CurrentMenu, EndString, 0, false, NAME_None, []()
 		{
+            M_ClearMenus();
 			gi->ExitFromMenu();
 		});
 

source/games/duke/src/game_misc.cpp

@@ -98,7 +98,7 @@ template <class func>
 void runtwoscreens(func completion)
 {
 	// shareware and TEN screens
-	if (!isShareware() && !isRR())
+	if (isShareware() && !isRR())
 		showtwoscreens(completion);
 	else completion(false);
 }