Ismo Puustinen authored Nov 10, 2017 and Beniamino Galvani committed Oct 19, 2018

Update nm-policy.c and nm-dns-manager.c so that the connection-specific
settings get propagated to DNS manger. Currently the only such value is
the mDNS status.

Add update_mdns() function to DNS plugin interface. If a DNS plugin
supports mDNS, it can set an interface with a given index to support
mDNS resolving or also register the current hostname.

The mDNS support is currently added only to systemd-resolved DNS plugin.

(cherry picked from commit 25906eda)