Turn off POSIX 2008 locales on AIX

[khwilliamson]

Fixes #23825

From the discussion in that ticket, it appears that the problem is the OS.

• This set of changes requires a perldelta entry, and it is included.

[Leont]

Possibly we should just add a proper configure flag for this?

[khwilliamson]

I don't understand @Leont 's comment. Please clarify

[tonycoz]

I don't understand @Leont 's comment. Please clarify

A ./Configure -Duse_posix_2008_locale_api flags, propagated to config.h. (Or logic inverted, but why add an extra negative?)

So aix.sh would do something like:

case "X$use_posix_2008_locale_api" in
X) use_posix_2008_locale_api=$undef
esac

which lets people test with it enabled.

I don't think it's reasonable to have Configure detect the kind of breakage the provoked this change.

But even without detection it would be a bigger change than this one.

[khwilliamson]

In some previous releases, I had a test i Configure to see if something about locales worked. The simplistic test ruled out egregious violations, but more subtle bugs in the platform's implementation went undetected. It was better to take that out and put it in the hints rather than misleadingly say it worked; which led to barking up the wrong tree during debugging.

[tonycoz]

yeah, I'm not suggesting that sort of probe, just that it has it's own Configure id that defaults define unless already set from the command-line or hints.

[Leont]

But even without detection it would be a bigger change than this one.

Yeah, I don't think my suggestion has to stop us from fixing locales on AIX first, but this way of wiring things is suboptimal for our users IMHO. Toggling it uses a surprising mechanism, and it isn't introspectable through %Config

[Leont]

just that it has it's own Configure id that defaults define unless already set from the command-line or hints.

Well, default to define if newlocale/freelocale/duplocale/uselocale/… are defined.

And arguably a uselocale option to go with it.