which: update 2.21 -> 2.23, build with meson

which: update 2.21 -> 2.23, build with meson

This (and 2.22) is a first release in many years. Rather than try
to use upstream's absurdly overblown, incompatible build system
(see below), I added a small-ish meson file. This means:

- drop tweaks and dependency on cwautomacros as that is no longer used

- drop patch as configure.ac has been rewritten, and the recipe is using meson anyway

- drop --disable-iberty for the same reason

In this realease, cwautomacros has been replaced by an equally custom, weird set
of macros, written by 'which' maintainer: https://github.com/CarloWood/cwm4

- one effect of that is that autoreconf isn't happy with which's configure.ac and won't run;
one is supposed to use a custom script instead: https://github.com/CarloWood/cwm4/blob/master/scripts/bootstrap.sh

- alas, that script is not shipped in tarballs; the maintainer wants
everyone to trust their 200k configure script (hello xz backdoor)

- building from git (where the script exists) is not impossible,
but that has no version tags

All this 'special handling' for what, exactly? Five .c files to produce one
single-function executable, and one manpage. Wich should all be in coreutils
to begin with. GNU's attachment to autotools defies reason.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>