libnet: ARP resending more robust with periodic events

Signed-off-by: Roni Häcki <roni.haecki@inf.ethz.ch>

libnet: added functionality to request ARP lookup sent from default q

In some cases we require the need to look up a MAC address from
another core than where the default networking queue is running.
This sends a message to the network stack started by the driver
and forces an ARP lookup request and waits for its completion
using Octopus.

Signed-off-by: Roni Häcki <roni.haecki@inf.ethz.ch>

octopus: remove include to flounder file in public include

Signed-off-by: Reto Achermann <reto.achermann@inf.ethz.ch>

libc: removing newlib, adding BSD libc
posixcompat: moving gettimeofday to libc
harness: adding a simple math test
lwip, lwip2: moving includes to /include, compiling with BSD headers

Signed-off-by: Adam Turowski <adam.turowski@inf.ethz.ch>

net/arp and net/dhcp: adding missing includes

Signed-off-by: Adam Turowski <adam.turowski@inf.ethz.ch>

libnet: don't install arp cache entries for IP 0.0.0.0

Signed-off-by: Reto Achermann <reto.achermann@inf.ethz.ch>

libnet: integrating arp service to library and adding test domains

Signed-off-by: Reto Achermann <reto.achermann@inf.ethz.ch>

libnet: adding functionality to publish/subscribe to ARPs

Signed-off-by: Reto Achermann <reto.achermann@inf.ethz.ch>