[db] remove four fonts from blacklist

* remove ``Skia.ttf`` cause the buggy AAT support was removed as of
  r4647.
* remove ``Diablindall.ttf`` is now read fine probably due to lazy
  loading (no idea if that means that the font actually works, it just
  stopped making Luatex crap itself in ``fontloader.open()``).
* ``LastResort.ttf`` supposedly works now as well.
* ``lingoes.ttf`` no longer crashes, cf.
  http://tracker.luatex.org/view.php?id=826.

There’s still a couple fonts left that I’ve never seen and which we
might remove from the blocklist as well.

Signed-off-by: Philipp Gesang <phg42.2a@gmail.com>
[db] display name of the blacklist file a font is blacklisted in