ovs-atomic: Delete atomic, atomic_flag, ovs_refcount destroy functions.

None of the atomic implementations need a destroy function anymore, so it's
"more standard" and more convenient for users to get rid of them.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Andy Zhou <azhou@nicira.com>

lib/netlink-socket.c

@@ -822,7 +822,6 @@ nl_dump_done(struct nl_dump *dump)
         ovs_assert(status);
         ofpbuf_uninit(&buf);
     }
-    atomic_destroy(&dump->status);
     nl_pool_release(dump->sock);
     seq_destroy(dump->status_seq);
     return status >> 1;