/usr/share/man/man3/XtRealloc.3.gz is in libxt-dev 1:1.1.5-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man3/XtMalloc.3.gz
/usr/share/man/man3/XtMalloc.3.gz