interfaces: lo: drop non-loopback frames
interfaces: lo: drop non-loopback frames

Drop packets silently on the loopback interface if they're not destined
for our host. This allows blackhole routing addresses by setting their
nexthop to the loopback interface.

satlab/libcsp,Psykar/kubos,kubostech/KubOS,satlab/libcsp,libcsp/libcsp,GomSpace/libcsp,pacheco017/libcsp,GomSpace/libcsp,pacheco017/libcsp,satlab/libcsp,GomSpace/libcsp,Psykar/kubos,Psykar/kubos,Psykar/kubos,Psykar/kubos,Psykar/kubos,pacheco017/libcsp,Psykar/kubos,pacheco017/libcsp,kubostech/KubOS,libcsp/libcsp