revised proposed time zone abbreviation changes

[Olson, Arthur David (NIH/NCI)]

> That "stdlen < 3" remains, I'd make it just be "if (stdlen == 0)"
> (for the error return).   < 0 is impossible the way the code is
> written, so there's no need to test that.   Anything > 0 in that
> context should be OK.

It might be best to simply remove the test, relying on the common-case code
to catch any problems.
(This would avoid surprises down the line involving a need to change two
length tests rather than one.)

				--ado