[REVIEW 3-5] duplicate fonts, one broken, one not, results in neither being detected

[Caolán McNamara]

i.e. https://bugs.freedesktop.org/show_bug.cgi?id=42901
and this commit to fix:
http://cgit.freedesktop.org/libreoffice/core/commit/?id=65a3ec97b5032d1748c8f84eeb0b8656e1c25918

broken duplicate seen before working duplicate, first rejected for being
broken, second rejected for being a duplicate. So remove broken fonts as
we go along allowing non-broken duplicate fonts to be processed.

C.