Qt should support reproducible builds

Some of the Qt's build time tools that generate source code add information about which source files where used for them. These get flagged by QA tests for reproducible builds (https://reproducible-builds.org/docs/build-path/)

The paths are only in comments, so the problem doesn't extend to binaries. However, at least Yocto builds package also all source code files and these include sources generated by rcc, qdbusxml2cpp and qtwaylandscanner that have build time paths in them.