Apparently this is needed for bionic libc.

This should fix:

  netlink_read: File exists
  netlink_read: No such process

/dev/arandom, which was previously used on OpenBSD, is not useful since
we're only using it for seeding the prng.

Signed-off-by: Stephane Glondu <steph@glondu.net>

This changes the semantics of filters: RTPROT_BOOT will now be redistributed,
but only if it is explicitly mentioned in a redistribute filter.