* wait() for the child process to die, let it rest in peace
* fix incorrect parentheses
* if there was no password on the command line or in .cnf file,
  pkt will be "", and we need to request the user to enter the password
* make sure that auth->salt is always allocated on a permanent memroot.
  when called from set_user_salt_if_needed(), user_copy and its auth_str
  are on the thd memroot, but auth_copy->salt is then copied to auth->salt
* adjust service files so that systemd wouldn't interfere with our
  setuid executables

also
* print the pam error message in debug mode