Roy Marples authored Jan 19, 2021 and Thomas Haller committed Jan 26, 2021

This locks NM into dhcpcd-9.3.3 as that is the first version to support
the --noconfigure option. Older versions are no longer supported by NM
because they do modify the host which is undesirable.

Due to the way dhcpcd-9 uses privilege separation and that it re-parents
itself to PID 1, the main process cannot be reaped or waited for.
So we rely on dhcpcd correctly cleaning up after itself.
A new function nm_dhcp_client_stop_watch_child() has been added
so that dhcpcd can perform similar cleanup to the equivalent stop call.

As part of this change, the STOP and STOPPED reasons are mapped to
NM_DHCP_STATE_DONE and PREINIT is mapped to a new state NM_DHCP_STATE_NOOP
which means NM should just ignore this state.

!668