Blacklisted fonts are listed one per line in a file named
"otfl-blacklist.cnf", there can be as much copies of this file as kpse
can find (we look for "tex" format despite of the file extension, so it
can exist any where a .tex file can) and all found files will be loaded
an read.
The parser is rather dump, it assumes a good formated file; one font
per line, no trailing spaces, no inline comments, lines starting with
"%" and empty lines will be ignored, any other lines will end in the
blacklist table without any further processing.