fonts/etc_fonts/conf.d/70-no-bitmaps.conf

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<!-- Reject bitmap fonts -->
 <selectfont>
  <rejectfont>
   <pattern>
     <patelt name="scalable"><bool>false</bool></patelt>
   </pattern>
  </rejectfont>
 </selectfont>
</fontconfig>