Error sending fax with defaults: Lock files attempted to be created in /var/lock

It looks like even on my host system (Fedora 34), `/var/lock` isn't writeable without privileges.

Maybe this locking mechanism should be removed altogether, or we choose another default directory?

Some references:

* https://unix.stackexchange.com/questions/278904/linux-file-hierarchy-whats-the-best-location-to-store-lockfiles
* https://tldp.org/HOWTO/Serial-HOWTO-13.html
* https://www.pathname.com/fhs/pub/fhs-2.3.html#VARLOCKLOCKFILES

It's starting to look like using `/var/lock` for serial devices is an outdated mechanism.