On Chimera Linux, which uses FreeBSD's userland tools, the original call
fails with the following error:
mktemp: mkstemp failed on /tmp/libfprint-XXXXXX.hwdb: Invalid argument
Moving the X's to the end of the template passed to `mktemp` fixes the
error, and also works with GNU's `mktemp`.
This solves various problems:
1. It stays the same also if some drivers have been disabled
2. It uses a stable path for being imported by systemd
3. It is still checked for its validity by tests
4. It can be auto-generated using a simple command