Comment 4 for bug 1166181

Ack on the sometimes need for C dependencies. I originally was going for the "build system knows best" design but there are always exceptions in real code :) So I'd like Bake to support the 99% case is easy with one variable, and it's possible to override this if necessary. Now we can tag variable values (for the optional support) we should probably allow the user to override values in the package list, i.e. something like:

programs.foo {
   sources = foo.vala
   packages = normal-package \
                        special-package (pkg-config-name=bar)
}