/usr/lib/x86_64-linux-gnu/ is in libkf5ksieve-dev 4:17.12.3-0ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/cmake/
/usr/lib/x86_64-linux-gnu/cmake/KF5LibKSieve/
/usr/lib/x86_64-linux-gnu/cmake/KF5LibKSieve/KF5LibKSieveConfig.cmake
/usr/lib/x86_64-linux-gnu/cmake/KF5LibKSieve/KF5LibKSieveConfigVersion.cmake
/usr/lib/x86_64-linux-gnu/cmake/KF5LibKSieve/KF5LibKSieveTargets-debian.cmake
/usr/lib/x86_64-linux-gnu/cmake/KF5LibKSieve/KF5LibKSieveTargets.cmake
/usr/lib/x86_64-linux-gnu/qt5/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/qt_KManageSieve.pri
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/qt_KSieve.pri
/usr/lib/x86_64-linux-gnu/qt5/mkspecs/modules/qt_KSieveUi.pri
/usr/lib/x86_64-linux-gnu/libKF5KManageSieve.so
/usr/lib/x86_64-linux-gnu/libKF5KSieve.so
/usr/lib/x86_64-linux-gnu/libKF5KSieveUi.so