[tz] [PROPOSED] Remove old Y2K code

[Paul.Koning at dell.com]

> On Jun 13, 2017, at 2:17 PM, Jonathan Lennox <lennox at cs.columbia.edu> wrote:
> 
> On Monday, June 12 2017, "Paul Eggert" wrote to "Brian.Inglis at SystematicSw.ab.ca, Time zone mailing list" saying:
> 
>> Perhaps you're right, I was too hasty. I brought back that code under 
>> the name you suggested, by installing the attached.
> 
> 
>> +    Y2K runtime checks are no longer enabled by default.  Add
>> +    -DDEPRECATE_TWO_DIGIT_YEARS to CFLAGS to enable them, instead of
>> +    adding -DNO_RUN_TIME_WARNINGS_ABOUT_YEAR_2000_PROBLEMS_THANK_YOU
>> +    to disable them.  (New name suggested by Brian Inglis.)
>> +
> 
> Since DEPRECATE_TWO_DIGIT_YEARS is used in an if statement, shouldn't this
> be -DDEPRECATE_TWO_DIGIT_YEARS=true ?  Otherwise it expands to
>    if ( && warn != IN_NONE ...
> 
> which obviously won't compile.

Not so, because -DFOO is equivalent to -DFOO=1 .

	paul