The TrackerExtractPersistence stuff takes care of marking files as ignored
whenever those trigger crashes. However for the files that simply error out
we just add those to a runtime blacklist, which gets forgotten on next runs.

Those will trigger message/warning logging each time tracker-extract is
restarted, which is more often now. Just mark those as failures as it'd
happen with files resulting in crashes. We need to think how these files
are generically retried after extractor fixes/updates, but that is also
missing for crashing files.

GNOME/tracker-miners#6

Closes: #6