fix Qt installation prefix
It must match 'qtdir' option in kdesrc-buildrc.
Otherwise, you have to edit qt6-build-include file and fully rebuild Qt so it could be installed in the place where it can be found.
It must match 'qtdir' option in kdesrc-buildrc.
Otherwise, you have to edit qt6-build-include file and fully rebuild Qt so it could be installed in the place where it can be found.