[cff] Allow `hlineto' and `vlineto' without arguments. We simply ignore such instructions. This is invalid, but it doesn't harm; and indeed, there exist such subsetted fonts in PDFs. Reported by Albert Astals Cid <aacid@kde.org>. * src/cff/cffgload.c (cff_decoder_parse_charstrings) [cff_op_hlineto]: Ignore instruction if there aren't any arguments on the stack.