sysmond-1.1.0

- This release changes the protocol.  Requests shorter than 1024 bytes
  are now ignored, so a forged request can never make sysmond send more
  data than it received.  sysmon3-3.1.0 or later is required.

- Each client address gets at most one reply every 900 milliseconds.

- sysmond now listens on both IPv4 and IPv6 (IPv4 only if the kernel
  was built without IPv6).

- Starting the daemon:
  - The PID file is locked, so a second instance refuses to start, and
    a PID file left behind by a crash no longer prevents a restart.
  - Errors such as the UDP port already being in use are reported to
    the terminal and in the exit status, so a bootscript or systemd
    sees the failure.
  - The PID file is written before the original process exits.
  - The daemon starts its own session and points stdin, stdout, and
    stderr at /dev/null.

- Signals:
  - SIGINT now stops the daemon like SIGTERM.
  - SIGHUP is now ignored; it used to kill the daemon and leave the
    PID file behind.

- Fix several crashes and hangs when a /proc or /sys file can't be
  read, including a hang on kernels without MemAvailable.
- Fix CPU counters overflowing on 32-bit systems.
- The CPU percentage now counts iowait as idle time, and irq, softirq,
  and steal time as busy time, so values may be slightly higher than
  before.
- The first CPU reading after startup now covers a full scan interval.
- Temperatures:
  - Sensors are listed in numeric order.
  - A sensor that can't be read is skipped instead of crashing the
    daemon.
  - Unlabeled sensors numbered 10 and above are now shown as temp10,
    temp11, and so on.
  - Reading temperatures no longer changes the daemon's working
    directory.
- All output is limited to the reply buffer size.  If there are too
  many temperature sensors to fit, whole lines are dropped and a
  message is written to the debug file.

- The debug file is only written if it is a regular file owned by
  root with no other names, so a hard link in /tmp can't redirect
  output into another file.

- The man page now documents the protocol, and a BLFS-style bootscript
  is included.

- Changes were made with substantial help from Claude.

