'pkgconf' is a source code project written to have the same
functionality as the freedesktop.org 'pkg-config' utility, but
without the complex dependency tree needed for compilation.

Whereas 'pkg-config' requires glib-2.0, which in turn (by default)
relies on pkg-config (causing a circular dependency), 'pkgconf'
has been written so it is pretty much the case of run:
  configure, make, make install

Project home page:

  http://pkgconf.org/

While, at the time of writing, the download link on the project page
was to an older version of the source code, adjusting the URL to be
the latest version (2.5.1) was found to also work

  wget https://distfiles.dereferenced.org/pkgconf/pkgconf-2.5.1.tar.gz

Note: You can also get the source code via github:

    https://github.com/pkgconf/pkgconf/archive/refs/tags/pkgconf-2.5.1.tar.gz

however it should be noted that these tar-balls unpack as
pkconfig-pkgconf-2.5.1, which would require a bit more work for
CASCADE-MAKE to work with, so the one use in this extension is the one
from the project site.