/usr/share/man/man1/camlp4rf.opt.1.gz is in camlp4-extra 4.01.0-3ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man1/camlp4.1.gz
/usr/share/man/man1/camlp4.1.gz