lwip: ipv6_addr: Render last zero in ip6addr_ntoa_r if not in first empty block
lwip: ipv6_addr: Render last zero in ip6addr_ntoa_r if not in first empty block

Upstream commit: ebd103775dcf1285c0eca87f83a0c48d0922da8b

johnkingsley/aprinter,ambrop72/aprinter,ambrop72/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,ambrop72/aprinter,ambrop72/aprinter,johnkingsley/aprinter,johnkingsley/aprinter,ambrop72/aprinter,ambrop72/aprinter,johnkingsley/aprinter,ambrop72/aprinter