ynl-gen-cpp: support for generating rt-link

This patch enables generation for rt-link and adds a simple application test in samples/.

Signed-off-by: Zibo Gong <gongzib@outlook.com>

Author: zb-gong

generated/Makefile

@@ -16,7 +16,7 @@ TOOL:=../ynl-gen-cpp.py
 GENS_PATHS=$(shell grep -nrI --files-without-match \
 		'protocol: netlink' ../Documentation/netlink/specs/)
 GENS_ALL=$(patsubst ../Documentation/netlink/specs/%.yaml,%,${GENS_PATHS})
-GENS=rt-addr $(filter-out devlink ovs_datapath ovs_flow ovs_vport nlctrl,${GENS_ALL})
+GENS=rt-addr rt-link $(filter-out devlink ovs_datapath ovs_flow ovs_vport nlctrl,${GENS_ALL})
 SRCS=$(patsubst %,%-user.cpp,${GENS})
 HDRS=$(patsubst %,%-user.hpp,${GENS})
 OBJS=$(patsubst %,%-user.cpp.o,${GENS})