Make stdio_mux compatible with Ubuntu bionic
Make stdio_mux compatible with Ubuntu bionic

This change explicitly passes in all arguments to the implicit
constructor of EpollData.

omegaup/omegajail,omegaup/omegajail,omegaup/omegajail,omegaup/omegajail,omegaup/omegajail,omegaup/omegajail,omegaup/omegajail,omegaup/omegajail,omegaup/omegajail,omegaup/omegajail,omegaup/omegajail