BDF comments are neither actually collected nor retrieved. There is
no need to be fancy with delimiters.
* src/bdf/bdflib.c (_add_bdf_comment): Delimit comments with zeros...
(bdf_load_font): ...and do not null-terminate comments additionally.
(_bdf_parse_glyphs): Check if comments are kept, which they are not.
(_bdf_parse_start): Minor clean up.