How to support adding pkg-config dependencies to a product

There should be an easy way to add pkg-config dependencies to a product. Currently it is possible to use PkgConfigProbe to get the raw information and the details can be hidden in a module, but it is difficult to implement this in a generic manner that allows for arbitrary pkg-config libraries to be added as dependencies of a product.

See this mailing list post for the original question that prompted the creation of this item:

http://lists.qt-project.org/pipermail/qbs/2017-February/001691.html