Qt 5.8 is immediately removed because its support window is ended.
The qtlocation module is built with `enableParallelBuilding = false` so that the
clipper library will be built before the components which link to it.
kjs now depends directly on pcre. The dependency was previously propagated from
qtbase, which now depends on pcre2.
- 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.
