Fixes the following link errors when Xen support is disabled:
build/release/net/native-stack.o: In function `net::add_native_net_options_description(boost::program_options::options_description&)':
/seastar/net/native-stack.cc:101: undefined reference to `get_xenfront_net_options_description()'
build/release/net/native-stack.o: In function `net::create_native_net_device(boost::program_options::variables_map)':
/seastar/net/native-stack.cc:93: undefined reference to `create_xenfront_net_device(boost::program_options::variables_map, bool)'
collect2: error: ld returned 1 exit status
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Simple discovery class + usage of it in the native stack init.
DHCP discovery will be default if no other ip options are set on command
line, and not explicitly turned off.
Signed-off-by: Calle Wilund <calle@cloudius-systems.com>
