Fix two potential read/write ordering problems (even though not yet seen in tests)

- Write operations could be 'stabilized' and previous versions could be
  purged from OSDs before the removal of version_override and following
  reads could potentially hit different version in EC pools
- Object was marked clean after completing the delete during recovery, so
  reads could in theory hit a deleted version and return nothing

src/osd.h

@@ -198,6 +198,7 @@ class osd_t
     void continue_primary_del(osd_op_t *cur_op);
     bool check_write_queue(osd_op_t *cur_op, pg_t & pg);
     void remove_object_from_state(object_id & oid, pg_osd_set_state_t *object_state, pg_t &pg);
+    void free_object_state(pg_t & pg, pg_osd_set_state_t **object_state);
     bool remember_unstable_write(osd_op_t *cur_op, pg_t & pg, pg_osd_set_t & loc_set, int base_state);
     void handle_primary_subop(osd_op_t *subop, osd_op_t *cur_op);
     void handle_primary_bs_subop(osd_op_t *subop);