/usr/lib/libACE_QtReactor.so is in libace-qtreactor-dev 6.2.8+dfsg-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libACE_QtReactor-6.2.8.so
/usr/lib/libACE_QtReactor-6.2.8.so