[tz] 1948-1951 Asia/Tokyo DST information

[Paul Eggert]

Phake Nick wrote:
> 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".

Those mean the same thing. Since DST ends at 00:00 the day after Saturday, the 
clock jumps back from 24:00 on Saturday to 23:00 on Saturday, and Saturday has 
25 hours.