This reverts commit 4cf0b6ba5d5ab5eb20a88449e0612f4dad8e4c29, reversing
changes made to 756b9c7d6caae3b02151642b85d84e9b4e4e9b17.
Qt 5.9.2 is reverted to Qt 5.9.1, as recommended by KDE upstream due to
https://bugreports.qt.io/browse/QTBUG-64017
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.
