[tz] Sri Lanka Standard Time

[Paul Eggert]

Matt Johnson wrote:
> Sri Lanka and India are both on UTC+05:30, but it would appear that Sri Lankans may be using the term "Sri Lanka Standard Time", abbreviated SLST.

As far as I can tell, there is no commonly used English-language abbreviation 
for the time in Sri Lanka. The database uses "LKT" for this abbreviation, but 
this abbreviation was invented back when I felt free to make things up, and 
nowadays I'd rather not encourage that sort of thing. So, let's instead change 
the abbreviation to "+0530". We can do that after the next release (which we'll 
need to do for Magadan) and things start to open up for less-urgent changes like 
this.