/usr/lib/libCEGUICommonDialogs-0.so is in libcegui-mk2-dev 0.8.4+dfsg-4ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libCEGUICommonDialogs-0.so.2
/usr/lib/libCEGUICommonDialogs-0.so.2