rewrite_node_address_for_bridge() doesn't set rs IPv6 addresses

rewrite_node_address_for_bridge() should set the IPv6 address in rs, as well as setting the one in ri. We can copy the code from ri.

This goes back to commit 9e9edf71 in tor 0.2.4.5-alpha.

This is unlikely to have caused any bugs since at least 0.2.8, because node_get_*_or_addr() checks the ri before the rs.

But let's fix it anyway, for consistency and better logging.

(Eventually, we will rip out this code when we make ri and rs read-only.)