[tz] 1948-1951 Asia/Tokyo DST information

It seems like the current info about past DST for Asia/Tokyo in tz database is incorrect. The law cited in the latest commit do say the DST en at 00:00 on the day after the second Saturday in September, however the second line of the law write that "the Second Saturday in September would have 25 hours in a day". I was made aware of it by reading an interview on NICT (The National Institute of Information and Communications Technology) of Japan and the history of DST in Japan given in the interview by NICT representative do said DST used to end at 25:00 there. See https://www.bengo4.com/internet/n_8461/