This is for when `notifications_local_only` was set true.

Closes #1902. Thanks to marcinkowskip.

This means libwebsockets < 2.4.0.

Closes #1814. Thanks to Odysseus1710.

- Add `MOSQ_OPT_TLS_USE_OS_CERTS` option, to instruct the client to load and  trust OS provided CA certificates for use with TLS connections.
- All clients now load OS provided CA certificates if used with `-L
  mqtts://...`, or if port is set to 8883 and no other CA certificates are
  used. Closes #1824.
- Add the `--tls-use-os-certs` option to all clients.

Closes #1824. Thanks to Jens Reimann.

Closes #1825. Thanks to Valentin Dimov.

Prevents use of invalid mutexes during mosquitto_destroy.

Closes #1914. Thanks to Nikolay Raspopov.

Seconds since the Unix epoch is not a parameter that can be obtained
with strftime on Windows.

Closes #1908. Thanks to Danil intl.