Try to remove assumption that zone's root vnode is marked VROOT

*** 409,419 ****
  rfs_climb_crossmnt(vnode_t **dvpp, struct exportinfo **exip, cred_t *cr)
  {
          struct exportinfo *exi;
          vnode_t *dvp = *dvpp;
  
!         ASSERT(dvp->v_flag & VROOT);
  
          VN_HOLD(dvp);
          dvp = untraverse(dvp);
          exi = nfs_vptoexi(NULL, dvp, cr, NULL, NULL, FALSE);
          if (exi == NULL) {
--- 409,419 ----
  rfs_climb_crossmnt(vnode_t **dvpp, struct exportinfo **exip, cred_t *cr)
  {
          struct exportinfo *exi;
          vnode_t *dvp = *dvpp;
  
!         ASSERT((dvp->v_flag & VROOT) || VN_IS_CURZONEROOT(dvp));
  
          VN_HOLD(dvp);
          dvp = untraverse(dvp);
          exi = nfs_vptoexi(NULL, dvp, cr, NULL, NULL, FALSE);
          if (exi == NULL) {
*** 488,498 ****
           * then the ".." refers beyond the root of an exported filesystem.
           */
          if (strcmp(da->da_name, "..") == 0 &&
              EQFID(&exi->exi_fid, (fid_t *)&fhp->fh_len)) {
                  if ((exi->exi_export.ex_flags & EX_NOHIDE) &&
!                     (dvp->v_flag & VROOT)) {
                          /*
                           * special case for ".." and 'nohide'exported root
                           */
                          if (rfs_climb_crossmnt(&dvp, &exi, cr) != 0) {
                                  error = NFSERR_ACCES;
--- 488,498 ----
           * then the ".." refers beyond the root of an exported filesystem.
           */
          if (strcmp(da->da_name, "..") == 0 &&
              EQFID(&exi->exi_fid, (fid_t *)&fhp->fh_len)) {
                  if ((exi->exi_export.ex_flags & EX_NOHIDE) &&
!                     ((dvp->v_flag & VROOT) || VN_IS_CURZONEROOT(dvp))) {
                          /*
                           * special case for ".." and 'nohide'exported root
                           */
                          if (rfs_climb_crossmnt(&dvp, &exi, cr) != 0) {
                                  error = NFSERR_ACCES;