The following adds /* <num> */ to dbg_line_numbers so there's the chance
to more easily lookup the ID of the match.pd line number used for
dumping when you want to debug a speicific replacement. It also cuts
the lines down to 10 entries.
* genmatch.cc (define_dump_logs): Make reverse lookup in
dbg_line_numbers easier by adding comments with start index
and cutting number of elements per line to 10.