[truetype] New function to skip the randomization tag.

* src/truetype/ttobjs.c (tt_skip_pdffont_random_tag):
New function to skip the randomization tag in the names of the
fonts embedded in a PDF.  It is used by tt_check_trickyness_family(),
to keep from mistaking "DLC" in the randomization tag as a
tricky font name. See discussion in:

https://lists.nongnu.org/archive/html/freetype-devel/2021-02/msg00002.html

For technical detail about the randomization tag, please find
PDF Reference 5.5.3 "Font Subsets".  Thanks to Justyna Wawrzynska
for pointing out the issue caused by the randomization tag.
1 file changed