Add a configuration to switch to monospace if spacing=100 is requested
Previously, requesting a monospace font with an invalid font family (for instance, when a font is not embedded in a PDF, poppler may issue such queries), the font family would be filled by configuration file 49-sansserrif.conf with sans-serif. This new rule set the family to monospace if spacing=100 is specified in the query.
Example query before:
% fc-match "Monospace821BT:spacing=100:lang=xx" file family DejaVu Sans:file=/usr/share/fonts/TTF/DejaVuSans.ttf
% fc-match "Monospace821BT:spacing=100:lang=xx" file family DejaVu Sans Mono:file=/usr/share/fonts/TTF/DejaVuSansMono.ttf
(Monospace821BT is a proprietary font used in some PDFs I have received, and this query has been generated by poppler)