/usr/ is in libgl1-mesa-glx 8.0.4-0ubuntu0.6.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/mesa/
/usr/lib/x86_64-linux-gnu/mesa/ld.so.conf
/usr/lib/x86_64-linux-gnu/mesa/libGL.so.1.2
/usr/lib/x86_64-linux-gnu/xorg/
/usr/lib/x86_64-linux-gnu/xorg/x11-extra-modules/
/usr/share/
/usr/share/doc/
/usr/share/doc/libgl1-mesa-glx/
/usr/share/doc/libgl1-mesa-glx/copyright
/usr/share/lintian/
/usr/share/lintian/overrides/
/usr/share/lintian/overrides/libgl1-mesa-glx
/usr/share/bug/
/usr/share/bug/libgl1-mesa-glx/
/usr/share/bug/libgl1-mesa-glx/script
/usr/share/bug/libgl1-mesa-glx/control
/usr/lib/x86_64-linux-gnu/mesa/libGL.so.1
/usr/share/doc/libgl1-mesa-glx/changelog.Debian.gz