/usr/share/man/man1/libpng-config.1.gz is in libpng12-dev 1.2.54-1ubuntu1.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man1/libpng12-config.1.gz
/usr/share/man/man1/libpng12-config.1.gz