/usr/include/x86_64-linux-gnu/ is in libqt5webkit5-dev 5.7.1+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/x86_64-linux-gnu/qt5/
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebDatabase
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebElement
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebElementCollection
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebFullScreenVideoHandler
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebHapticFeedbackPlayer
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebHistory
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebHistoryInterface
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebHistoryItem
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebKitPlatformPlugin
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebNotificationData
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebNotificationPresenter
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebPluginFactory
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebSecurityOrigin
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebSelectData
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebSelectMethod
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebSettings
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebSpellChecker
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QWebTouchModifier
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QtWebKit
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QtWebKitDepends
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/QtWebKitVersion
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qtwebkitversion.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebdatabase.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebelement.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebhistory.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebhistoryinterface.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebkitglobal.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebkitplatformplugin.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebpluginfactory.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebsecurityorigin.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKit/qwebsettings.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QGraphicsWebView
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QWebFrame
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QWebHitTestResult
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QWebInspector
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QWebPage
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QWebView
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QtWebKitWidgets
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QtWebKitWidgetsDepends
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/QtWebKitWidgetsVersion
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/qgraphicswebview.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/qtwebkitwidgetsversion.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/qwebframe.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/qwebinspector.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/qwebpage.h
/usr/include/x86_64-linux-gnu/qt5/QtWebKitWidgets/qwebview.h