/usr/share/man/man3/wl_proxy_set_user_data.3.gz is in libwayland-dev-lts-trusty 1.4.0-1ubuntu1~precise2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man3/wl_proxy.3.gz
/usr/share/man/man3/wl_proxy.3.gz