Allow mDNS on IFF_POINTOPOINT interfaces

Instead of disallowing mDNS on interfaces that specify IFF_POINTOPOINT,
the code should check for the presence of IFF_MULTICAST instead. It is
perfectly valid to support mDNS on point-to-point links, such as IPv6
over BLE networks, if they support multicast.

Change-Id: I282a039483ad1d677d31e5169d53bbae25a1c9c4
Test: TH
2 files changed