Add a debug mode to pkt-loop-filter that outputs debug messages for every
dropped packet (with the reason it was dropped). Also add a small script to
read the kernel trace pipe, after making sure tracing is active (otherwise
there will be no output in the pipe).
The source MAC address+VLAN is squeezed into a single u64 when printing as
a quick workaround to the lack of MAC address printing in BPF printk.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>