[tz] make rearguard_tarballs fails on macOS

[Paul Gilmartin]

On 2020-10-16, at 22:09:19, Deborah Goldsmith via tz <tz at iana.org> wrote:
> 
> This is on the latest version of macOS. While Darwin has a lot of content from FreeBSD, there’s no effort to keep the two in sync AFAIK. According to Wikipedia Darwin is not POSIX-compatible but is compatible with the Single UNIX Specification, version 3.
>  
It seems to be in current Single UNIX:
    -d  date_time
    Use the specified date_time instead of the current time. The option-argument shall be a string of the form:
    YYYY-MM-DDThh:mm:SS[.frac][tz]
or:
    YYYY-MM-DDThh:mm:SS[,frac][tz]
    ...
    -t  time
    Use the specified time instead of the current time. The option-argument shall be a decimal number of the form:
    [[CC]YY]MMDDhhmm[.SS]

Why do we need both?  Existing Art, I suppose.

RATIONALE
    ...
	• In System V, an ambiguity exists when a pathname that is a decimal number leads the operands; it is treated as a time value. In BSD, no time value is allowed; files may only be touched to the current time. The -t time construct solves these problems for future conforming applications (note that the -t option is not historical practice).

> I’ll just patch the Makefile and then patch the output to remove the “dirty”.

-- gil