It appears that the values defined for RPL_NODE_IS_ROOT and
RPL_MAX_ROUTING_ENTRIES in the Makefile via CFLAGS are not recognized in
sc_rpl.c (my guess: they are only visible to the rpl module?)
Therefore RPL_MAX_ROUTING_ENTRIES is always set to 0, no matter how the
binary is compiled, thus resulting in the output "No routing table
available" for root nodes.