[Server] Fix type name warning for Player

The warning in Visual Studio was: "'Player': type name first seen using 'class' now seen using 'struct'"

apps/openmw-mp/Player.hpp

@@ -21,7 +21,6 @@
 #include "Cell.hpp"
 #include "CellController.hpp"
 
-struct Player;
 typedef std::map<RakNet::RakNetGUID, Player*> TPlayers;
 typedef std::map<unsigned short, Player*> TSlots;