Use the RTMGRP_IPV4_ROUTE const from x/sys/unix instead of using the
corresponding RTNLGRP_IPV4_ROUTE const to create the multicast groups
mask.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
The sticky socket code stays in the device package for now,
as it reaches deeply into the peer list.
This is the first step in an effort to split some code out of
the very busy device package.
Signed-off-by: David Crawshaw <crawshaw@tailscale.com>