export environment variable for package on which depgen is run

[ignatenkobrain]

After offline discussion with @ffesti and @Conan-Kudo, it seems that RPM runs depgens per package and seems that rpmfc has information on which package it runs depgen. So we can just export some environment variables which would represent a package so depgens can take advantage of knowing this information.

I will try to hack some impl for this.

[ignatenkobrain]

@n3npq that's implementation detail (envvar vs macro).

[ignatenkobrain]

@n3npq imagine that you split -devel into -devel + -static packages. My idea was to add pkg-config file to both packages, but make sure that -devel depends on Requires stuff while -static depends on both Requires and Requires.private.

There are more use-cases in Python / Rust worlds, but this pkg-config was the simplest one I could come up with.

[ignatenkobrain]

well, you already have Provides: pkgconfig(foo), so we could do something like Requires: (pkgconfig(bar) if pkgconfig-static(foo)). It might be not perfect, but it is doable even today.