tc: add cls_bpf frontend

This is the iproute2 part of the kernel patch "net: sched:
add BPF-based traffic classifier".

[Will re-submit later again for iproute2 when window for
 -next submissions opens.]

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Thomas Graf <tgraf@suug.ch>
2 files changed