[Pkg-config](https://en.wikipedia.org/wiki/Pkg-config) is a way for shared libraries to declare the compiler flags needed to use them. There are two different ways of generating Pkg-config files in Meson. The first way is to build them manually with the `configure_files` command. The second way is to use Meson's built in Pkg-config file generator. The difference between the two is that the latter is very simple and meant for basic use cases. The former should be used when you need to provide a more customized solution.