api: libhttpserver-based server

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
stub setsid

Same as fork, vfork, etc. So goes in the same place.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>