broken before because of too-strict filters.
Move setup_signals under the seccomp filter to give it more testing coverage.
Make the UDP datagram length check much more strict. If the read buffer
does not match up with the header lengths exactly, it is discarded.
Print a warning to syslog/stdout when ifchd execute_buffer() returns an
error.
Fix a regression introduced in ifchd that would cause the epoll handler to
spin when a client connection closed.
