/usr/lib/x86_64-linux-gnu/ is in libmutter-dev 3.22.3-2.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/libmutter.so
/usr/lib/x86_64-linux-gnu/mutter/
/usr/lib/x86_64-linux-gnu/mutter/Cally-1.0.gir
/usr/lib/x86_64-linux-gnu/mutter/Clutter-1.0.gir
/usr/lib/x86_64-linux-gnu/mutter/ClutterX11-1.0.gir
/usr/lib/x86_64-linux-gnu/mutter/Cogl-1.0.gir
/usr/lib/x86_64-linux-gnu/mutter/CoglPango-1.0.gir
/usr/lib/x86_64-linux-gnu/mutter/Meta-3.0.gir
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/libmutter.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/mutter-clutter-1.0.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/mutter-clutter-x11-1.0.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/mutter-cogl-1.0.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/mutter-cogl-pango-1.0.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/mutter-cogl-path-1.0.pc