Check subcommands' statuses

[smoelius]

See #407 (comment).

[smoelius]

@vanhauser-thc afl.rs could have a special case for afl-system-config, but would you consider adding something like:

if [ $# -ne 0 ]; then
  echo "Unknown option(s): $@"
  exit 1
fi

here?

[vanhauser-thc]

@vanhauser-thc afl.rs could have a special case for afl-system-config, but would you consider adding something like:

if [ $# -ne 0 ]; then
  echo "Unknown option(s): $@"
  exit 1
fi

here?

done in 7e67dc9d6938aadef19d5697a448cdf15a50172f

[smoelius]

done in 7e67dc9d6938aadef19d5697a448cdf15a50172f

Thank you, @vanhauser-thc.