Corrections of zone.tab for CN entries

[yaoz at vidar.niaaa.nih.gov]

> From eggert at twinsun.com Wed Dec 12 19:49:16 2001
> 
> CN	+3114+12128	Asia/Shanghai	east China - Beijing, Guangdong, Shanghai, etc.
> CN	+4545+12641	Asia/Harbin	Heilongjiang
> CN	+2934+10635	Asia/Chongqing	central China - Gansu, Guizhou, Sichuan, Yunnan, etc.
> CN	+4348+08735	Asia/Urumqi	Tibet & most of Xinjiang
> CN	+3929+07559	Asia/Kashgar	southwest Xinjiang
 
This is great.

My initial confusion comes from this: All China is really under one official
time ("Beijing time" in Chinese), why all those different zones?  After
looking at glibc/libc/timezone/asia, I realized that zone.tab goes far
beyond the current time zone.  For it, if two regions historically use
different times, they are considered in two time zones, even though they
don't have any time difference now.  This would certainly help if someone
tries to ask, say, what time was it in Beijing at 8pm May 12, 1940 in
Chongqing?