add vlan_learning and distributed_bridge in libbcc package

Signed-off-by: Yonghong Song <yhs@plumgrid.com>

examples/CMakeLists.txt

-set(EXAMPLE_FILES hello_world.py task_switch.py task_switch.c simple_tc.py)
+set(EXAMPLE_FILES hello_world.py task_switch.py task_switch.c simple_tc.py
+                  simulation.py vlan_learning.py vlan_learning.c)
 install(FILES ${EXAMPLE_FILES} DESTINATION share/bcc/examples)
+
+add_subdirectory(distributed_bridge)

examples/distributed_bridge/CMakeLists.txt

+set(EXAMPLE_FILES main.py simulation.py tunnel_mesh.py tunnel.py
+                  tunnel.c tunnel_mesh.c)
+install(FILES ${EXAMPLE_FILES} DESTINATION share/bcc/examples/distributed_bridge)