/usr/lib/x86_64-linux-gnu/pkgconfig/cucul.pc is in libcaca-dev 0.99.beta18-1ubuntu5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/pkgconfig/caca.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/caca.pc