Test for GNU/XSI version of strerror_r

[Ian Pilcher]

On 10/4/19 2:37 PM, Florian Weimer wrote:
> You could use generic selection and _Generic.  But these days, that's
> more restrictive than C++ in terms of compiler support.

I only care about gcc, but I do need to support 4.8.5 (in EL7), so it
looks like that isn't an option.

> It's not really defined to add “#define _GNU_SOURCE” after the first
> #include, so you could probably just check for _GNU_SOURCE.

I'm actually doing that as well.  I just wanted to catch the (admittedly
pathological) case where Python.h includes string.h *before* defining
_GNU_SOURCE.

Here's what I've got so far.  (It looks like my 100-line estimate may
have been a bit low.  Gotta love C!)

   https://pastebin.com/WBH1FPwC

-- 
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Ian Pilcher                                         arequipeno@gmail.com
-------- "I grew up before Mark Zuckerberg invented friendship" --------
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