* receive SIGCHLD when child is stopped & restarted (e.g. SIGSTOP / SIGCONT) ?? -> that would mess up wait_chld()?  ==> actually OK because waitpid() doesn't pick it up
  ==> BUT risk of affecting main fcron process by repeatedly calling SIGCONT on child fcron process, which is run as the user (so they can signal it)?
  use sigaction() instead of signal() and add flag to ignore child STOP/CONT ?

