QLibraryPrivate: Actually merge load hints
Or old and new load hints in mergeLoadHints() instead of just storing new ones. Andjust QLibraryPrivate::setLoadHints() to handle objects with no file name differently and just set load hints directly.
Mention that load hints are merged once the file name is set in the documentation for QLibrary::setLoadHints().
Add a regression test into tst_qfactoryloader.
Update and extend tst_QPluginLoader::loadHints() to take into account load hints merging.
Fixes: QTBUG-114480 Change-Id: I3b9afaec7acde1f5ff992d913f8d7217392c7e00 Reviewed-by: Qt CI Bot qt_ci_bot@qt-project.org Reviewed-by: Thiago Macieira thiago.macieira@intel.com