shared library for pkgconf

 pkgconf is a replacement for pkg-config, a system for managing library
 compile and link flags that works with automake and autoconf.
 .
 pkgconf does not bundle any third-party libraries or depend on any
 third-party libraries.
 .
 libpkgconf is a library which provides access to most of pkgconf's
 functionality, to allow other tooling such as compilers and IDEs to
 discover and use libraries configured by pkgconf.
 .
 This package ships a shared library for libpkgconf.