parser: make base classes for rules using prefixes and perms and use them

Cleanup the parse code by making shared prefix and perms classes for
rules and convert rules to use them.

Signed-off-by: John Johansen <john.johansen@canonical.com>

parser/af_unix.h

@@ -46,6 +46,13 @@ public:
 		free(peer_addr);
 	};
 
+	virtual bool valid_prefix(prefixes &p, const char *&error) {
+		if (p.owner) {
+			error = "owner prefix not allowed on unix rules";
+			return false;
+		}
+		return true;
+	};
 	virtual bool has_peer_conds(void) {
 		return af_rule::has_peer_conds() || peer_addr;
 	}