/usr/share/doc/libgtk-3-0-dbg/README.gz is in libgtk-3-0-dbg 3.14.5-1+deb8u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libgtk-3-0-dbg/../libgtk-3-common/README.gz
/usr/share/doc/libgtk-3-0-dbg/../libgtk-3-common/README.gz