* Remove `mesa` as dependency; `qt5-base` and `qt6-base` both depend on it
and none of the projects depend on it directly; official Qt-based
packages like `qtcreator` also don't depend on `mesa`
* Add `libx11` as dependency of `qtutilities` and variants as it is
actually used directly by those packages for the capslock detection (even
though that feature was broken for quite some time)
* Use an older glibc so resulting binaries can run
on older systems (without having to link statically
against glibc)
* Call packages static-compat-* to make it clear that
these packages are intended for compatibility with
older distributions
* Add further libraries to get static-compat-qt6-base
and some other static-compat-qt6-* packages building