/usr/share/doc/linux-tools-lowlatency-lts-vivid/changelog.gz is in linux-tools-lowlatency-lts-vivid 4.4.0.21.22.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/linux-tools-lowlatency-lts-vivid/../linux-tools-lowlatency/changelog.gz