d_linkage is largely done (#176)

include/d/a/obj/d_a_obj_ring.h

@@ -4,7 +4,6 @@
 #include "d/a/obj/d_a_obj_base.h"
 #include "m/m3d/m_smdl.h"
 #include "s/s_State.hpp"
-#include "s/s_StateMgr.hpp"
 
 class dAcOring_c : public dAcObjBase_c {
 public:
@@ -24,8 +23,6 @@ public:
     }
 
 private:
-    static u32 ROT_PER_TICK;
-
     m3d::smdl_c mModel;
     STATE_MGR_DECLARE(dAcOring_c);
     u8 field_0x388;