In many networking tests we had to configure SLIP in the prj.conf
leaving those configurations Qemu specific. This change enables SLIP for
QEMU targets automatically and allows reuse of prj.conf for multiple
boards.
Additionally, the TUN options is removed. This option was not used
anywhere.
To enable self-contained networking tests that do not depend on SLIP, we
introduce the new option NET_TEST which disables TAP and allows testing
in QEMU without the need for a host interface.
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
Aska Wu