gnrc_networking: add ng_rpl to example

examples/gnrc_networking/Makefile

@@ -22,11 +22,12 @@ USEMODULE += auto_init_ng_netif
 # Specify the mandatory networking modules for IPv6 and UDP
 USEMODULE += ng_ipv6_router_default
 USEMODULE += ng_udp
+# Add a routing protocol
+USEMODULE += ng_rpl
 # This application dumps received packets to STDIO using the pktdump module
 USEMODULE += ng_pktdump
 # Additional networking modules that can be dropped if not needed
 USEMODULE += ng_icmpv6_echo
-USEMODULE += fib
 # Add also the shell, some shell commands (which are based on uart0 in this app)
 USEMODULE += uart0
 USEMODULE += shell