(svn r5614) Move a type declaration to its only user

vehicle.c

@@ -593,6 +593,7 @@ void VehicleEnteredDepotThisTick(Vehicle *v)
 	}
 }
 
+typedef void VehicleTickProc(Vehicle*);
 static VehicleTickProc* _vehicle_tick_procs[] = {
 	Train_Tick,
 	RoadVeh_Tick,

vehicle.h

@@ -242,7 +242,6 @@ struct Vehicle {
 #define IS_CUSTOM_FIRSTHEAD_SPRITE(x) (x == 0xFD)
 #define IS_CUSTOM_SECONDHEAD_SPRITE(x) (x == 0xFE)
 
-typedef void VehicleTickProc(Vehicle *v);
 typedef void *VehicleFromPosProc(Vehicle *v, void *data);
 
 void VehicleServiceInDepot(Vehicle *v);