[tz] New Abbreviation needed for Asia/Pyongyang

[Paul Eggert]

Greg Slayden wrote:
> I noticed in the 2015f tz database that the new Asia/Pyongyang zone for North Korea (now UTC+8:30) has the same abbreviation as Asia/Seoul.  Both are noted as KST.

Yes, the matter was discussed, and as the database already used KST for 
UTC+08:30 in Korea we decided to just keep doing that.  Abbreviations need not 
be unambiguous.