In particular, this moves share/kf5 to the "out" output. This prevents
kdelibs4support from pulling kdoctools.dev into its closure (via
share/kf5/kdoctools/customization/dtd/kdex.dtd, which references
${kdoctools}/share/kf5).
This reduces the closure size of kdelibs4support by 156 MiB.
- Reduce environment pollution with a separate $bin output containing programs,
plugins, and shared data. Libraries remain in $out and are not installed into
the environment.
- Only propagate build inputs as required.
