The initial implementation of toDhcpResults attempted to get the
leased IP address from ciaddr if yiaddr was 0.0.0.0, but it never
actually did so because a) it used == instead of equals(), and b)
the parsing code never populated mClientIp for a DhcpOfferPacket
or DhcpAckPacket.
Fix this and add a test for it.. Technically DHCP does not use
ciaddr (only bootp uses it), but in 5.0 we would use ciaddr if
yiaddr was 0.0.0.0 and a bit more compatibility shouldn't hurt.
Bug: 19704592
Change-Id: I1f58555f0c10b9c576995a6edb759a83d8938ea0
f68edb1611