/usr/share/doc/libgdk3.0-cil-dev/changelog.Debian.gz is in libgdk3.0-cil-dev 2.99.3-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgdk3.0-cil-dev/../libcairo1.10-cil/changelog.Debian.gz