Archive uses native row format, so honestly this is just the change in a flag.
sql/ha_archive.h:
Added bit field support (and dropped the ha_not_exact_count since we always have this).
mysql-test/r/archive_bitfield.result:
New BitKeeper file ``mysql-test/r/archive_bitfield.result''
mysql-test/t/archive_bitfield.test:
New BitKeeper file ``mysql-test/t/archive_bitfield.test''