disable downgrade and not enforced rule messages by default

Currently the apparmor parser warns about rules that are not enforced or
downgraded. This is a problem for distros that are not carrying the out of
tree kernel patches, as most profile loads result in warnings.

Change the behavior to not output a message unless a warn flag is passed.
This patch adds 2 different warn flags
  --warn rule-downgraded    	 # warn if a rule is downgraded
  --warn rule-not-enforced	   # warn if a rule is not enforced at all

If the warnings are desired by default the flags can be set in the
parser.conf file.

v2 of patch
- update man page
- add --warn to usage statement
- make --quiet clear warn flags

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Steve Beattie <steve@nxnw.org>

parser/parser_interface.c

@@ -442,7 +442,7 @@ void sd_serialize_profile(std::ostringstream &buf, Profile *profile,
 			sd_write_uint16(buf, profile->net.deny[i] & profile->net.quiet[i]);
 		}
 		sd_write_arrayend(buf);
-	} else if (profile->net.allow)
+	} else if (profile->net.allow && (warnflags & WARN_RULE_NOT_ENFORCED))
 		pwarn(_("profile %s network rules not enforced\n"), profile->name);
 
 	if (profile->policy.dfa) {