Re: Cleaning up historical portability baggage

Hi,

Here's another set patches for cruft I discovered going line-by-line through
the autoconf vs meson test differences. They'd all be simple to port to meson
too, but I think it's better to clean them up.

0001: __func__ is C99, so we don't need to support fallbacks

0002: windows: We've unconditionally defined HAVE_MINIDUMP_TYPE for msvc forever, we
can rely on it for mingw too

0003: aix: aix3.2.5, aix4.1 are not even of historical interest at this point
- 4.1 was released before the first commit in our commit history

0004: solaris: these gcc & gnu ld vs sun stuff differences seem unnecessary or
outdated

I started this because I wanted to get rid of with_gnu_ld, but there's still
a necessary reference left unfortunately. But it still seems worth doing?

I checked and the relevant options (-shared, -Wl,-Bsymbolic, -Wl,-soname)
work even on solaris 10 with developerstudio12.5 (not the latest)

0005: those broken system headers look to have been repaired a good while ago,
or, in the case of irix, we don't support the platform anymore

Greetings,

Andres Freund