This is needed for the stability aware code.

Stress the asymmetry with timeval_add_msec, which is purely functional.

Stress the asymmetry with timeval_add_msec, which is purely functional.

Pointless, but clearer to me.

This protects against clock stepping if CLOCK_MONOTONIC is implemented.

Recent kernels don't include RTA_DST in the default route.  This fixes
incorrect parsing of such entries.  Reported by Robert Lukan.

This saves 512 bytes of BSS.

This would cause an infinite loop when the clock was stepped.

On linux, listen to address and link change events using the netlink socket,
and react to them by dumping all local addresses or all local interfaces,
respectively, to keep babel's view up to date.
This breaks MacOS, as kernel_socket.c needs to grow a kernel_addresses()
function.