Polyobjects: add po_movecount member to mobj_t instead of using lastlook

- Polyobject carrying set lastlook on mobjs for internal
  tracking
- lastlook is used by some objects to track their own
  state
- Ring Shooter uses lastlook to remember which player
  summoned it
- A Ring Shooter spawned right next to a polyobject would
  become buggy; If its owner player pressed the respawn
  button again before the Ring Shooter despawned, that
  player would be teleported back to the Ring Shooter
  instead of spawning a new Ring Shooter (which would be
  the correct behavior)

Nep: We don't have a ring shooter but this would still be a useful fix

src/p_mobj.h

@@ -448,6 +448,8 @@ struct mobj_t
 	INT32 script_args[NUM_SCRIPT_ARGS];
 	char *script_stringargs[NUM_SCRIPT_STRINGARGS];
 
+	INT32 po_movecount; // Polyobject carrying (NOT savegame, NOT Lua)
+
 	// WARNING: New fields must be added separately to savegame and Lua.
 };
 

src/p_polyobj.c

@@ -882,14 +882,10 @@ static void Polyobj_carryThings(polyobj_t *po, fixed_t dx, fixed_t dy)
 
 			for (; mo; mo = mo->bnext)
 			{
-				// lastlook is used by the SPB to determine targets, do not let it affect it
-				if (mo->type == MT_SPB)
+				if (mo->po_movecount == pomovecount)
 					continue;
 
-				if (mo->lastlook == pomovecount)
-					continue;
-
-				mo->lastlook = pomovecount;
+				mo->po_movecount = pomovecount;
 
 				// Don't scroll objects that aren't affected by gravity
 				if (mo->flags & MF_NOGRAVITY)
@@ -1118,14 +1114,10 @@ static void Polyobj_rotateThings(polyobj_t *po, vector2_t origin, angle_t delta,
 
 			for (; mo; mo = mo->bnext)
 			{
-				// lastlook is used by the SPB to determine targets, do not let it affect it
-				if (mo->type == MT_SPB)
+				if (mo->po_movecount == pomovecount)
 					continue;
 
-				if (mo->lastlook == pomovecount)
-					continue;
-
-				mo->lastlook = pomovecount;
+				mo->po_movecount = pomovecount;
 
 				// Don't scroll objects that aren't affected by gravity
 				if (mo->flags & MF_NOGRAVITY)