/usr/include/x86_64-linux-gnu/ is in libubuntugestures5-gles-dev 1.3.1918+16.04.20160404-0ubuntu3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/x86_64-linux-gnu/qt5/
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/CandidateInactivityTimer
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/DebugHelpers
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/Pool
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/TimeSource
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/Timer
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/TouchOwnershipEvent
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/TouchRegistry
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/UbuntuGestures
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/UbuntuGesturesDepends
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/UbuntuGesturesVersion
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/UnownedTouchEvent
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/candidateinactivitytimer.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/debughelpers.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/pool.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/timer.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/timesource.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/touchownershipevent.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/touchregistry.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/ubuntugesturesglobal.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/ubuntugesturesversion.h
/usr/include/x86_64-linux-gnu/qt5/UbuntuGestures/unownedtouchevent.h