/usr/lib/libCEGUINullRenderer.so is in libcegui-mk2-dev 0.7.5-8.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libCEGUINullRenderer-0.7.5.so
/usr/lib/libCEGUINullRenderer-0.7.5.so