Deprecated the functions rtnl_qdisc_change() and
rtnl_qdisc_build_change_request() for their lack of being able to
specify flags. The new functions rtnl_qdisc_update() and
rtnl_qdisc_build_update_request() may be used instead. The old
functions are still available though. However, rtnl_qdisc_update()
no longer implies NLM_F_REPLACE, it has to specified implicitely
to allow updating a qdisc without risking to replace another qdisc.
Included detailed documentation of qdisc addition/update/deletion.
Introduced APPBUG() macro to let application developer know of
API abuse.
747b892c91