/usr/share/doc/libmysql-cil-dev/changelog.Debian.gz is in libmysql-cil-dev 6.4.3-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libmysql-cil-dev/../libmysql6.4-cil/changelog.Debian.gz