/usr/ is in libfolks-dev 0.9.5-1ubuntu5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/vala/
/usr/share/vala/vapi/
/usr/share/
/usr/share/doc/
/usr/share/doc/libfolks-dev/
/usr/share/doc/libfolks-dev/copyright
/usr/share/vala/vapi/folks.deps
/usr/share/vala/vapi/folks.vapi
/usr/share/gir-1.0/
/usr/share/gir-1.0/FolksTelepathy-0.6.gir
/usr/share/gir-1.0/Folks-0.6.gir
/usr/share/gir-1.0/FolksEds-0.6.gir
/usr/include/
/usr/include/folks/
/usr/include/folks/folks.h
/usr/lib/
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/folks.pc
/usr/share/doc/libfolks-dev/changelog.Debian.gz
/usr/lib/x86_64-linux-gnu/libfolks.so