pkgconf: upgrade 1.9.3 -> 1.9.4

Changes from 1.9.3 to 1.9.4:
----------------------------

* Fix a buffer overflow vulnerability involving very large variable expansions.
  CVE-2023-24056

* Fix a bunch of minor regressions with the solver.

* Create separate solutions for `--cflags` and `--libs` when `--static` is not
  used.

* Remove final trailing whitespace in pkgconf_fragment_render_buf().

* Revert broken pkg.m4 change involving querying module versions in
  PKG_CHECK_MODULES.

* Fix handling of tildes in version strings.

* Various C99 formatting string fixes involving SIZE_FMT_SPECIFIER.

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit ea19dd90)
Signed-off-by: Steve Sakoman <steve@sakoman.com>