// If flags contain wxEXEC_SYNC, return -1 on failure and the exit code of the
// process if everything was ok. Otherwise (i.e. if wxEXEC_ASYNC), return 0 on
// failure and the PID of the launched process if ok.
// If flags contain wxEXEC_SYNC, return -1 on failure and the exit code of the
// process if everything was ok. Otherwise (i.e. if wxEXEC_ASYNC), return 0 on
// failure and the PID of the launched process if ok.