Unclear error message with typo ptrace (traceby)

[Cameron Norman]

When I include the rule `ptrace (traceby)` the resuting error message (it should be tracedby) could be a little more clear:

    AppArmor parser error for usr.lib.bamf.bamfdaemon in usr.lib.bamf.bamfdaemon at line 34: Internal: unexpected ptrace mode character 't' in input

Rather than use the character I think it would be best to give the whole string. Especially since you can have `trace` in addition.