Have urlutil_p.h follow the move of its consumer code
Call of UrlUtil::firstChildUrl was moved to gui library in fdacbf4e
Removing the respective unneeded include from kurlnavigator.cpp in the first commit cleans up the
/builds/frameworks/kio/src/filewidgets/urlutil_p.h:47:13: warning: ‘QUrl KIO::UrlUtil::firstChildUrl(const QUrl&, const QUrl&)’ defined but not used [-Wunused-function]
47 | static QUrl firstChildUrl(const QUrl &lastUrl, const QUrl ¤tUrl)