/usr/share/doc/libclang-3.9-dev/changelog.Debian.gz is in libclang-3.9-dev 1:3.9.1-19ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libclang-3.9-dev/../libllvm3.9/changelog.Debian.gz