Fix NFS design problems re. multiple zone keys
Make NFS server zone-specific data all have the same lifetime
Fix rfs4_clean_state_exi
Fix exi_cache_reclaim
Fix mistakes in zone keys work
More fixes re. exi_zoneid and exi_tree
(danmcd -> Keep some ASSERT()s around for readability.)

*** 167,176 ****
--- 167,177 ----
          exi->exi_count = 1;
          /* Caller will set exi_zone... */
          exi->exi_volatile_dev = (vfssw[vp->v_vfsp->vfs_fstype].vsw_flag &
              VSW_VOLATILEDEV) ? 1 : 0;
          mutex_init(&exi->exi_lock, NULL, MUTEX_DEFAULT, NULL);
+         exi->exi_zoneid = ne->ne_globals->nfs_zoneid;
  
          /*
           * Build up the template fhandle
           */
          exi->exi_fh.fh_fsid = fsid;
*** 838,848 ****
--- 839,860 ----
          treenode_t *connect_point = NULL;
  
          ASSERT(RW_WRITE_HELD(&ne->exported_lock));
          ASSERT(curzone == exip->exi_zone || curzone == global_zone);
  
+         /*
+          * exi_tree can be null for the zone root
+          * which means we're already at the "top"
+          * and there's nothing more to "climb".
+          */
          tnode = exip->exi_tree;
+         if (tnode == NULL) {
+                 /* Should only happen for... */
+                 ASSERT(exip == ne->exi_root);
+                 return;
+         }
+ 
          /*
           * The unshared exportinfo was unlinked in unexport().
           * Zeroing tree_exi ensures that we will skip it.
           */
          tnode->tree_exi = NULL;