libsepol: Do not reject all type rules in conditionals when validating

Commit 1c91bc8 ("libsepol: reject self flag in type rules in old
policies") actually rejects all type rules in conditionals in modular
policies prior to version 21 (MOD_POLICYDB_VERSION_SELF_TYPETRANS).

The problem is because of fall-through in a switch statement when
the avrule flags are 0. Instead, break rather than fall-through when
avrule flags are 0.

Reviewed-by: Christian Göttsche <[email protected]>
Acked-by: Petr Lautrbach <[email protected]>

Author: jwcart2

libsepol/src/policydb_validate.c

@@ -1076,6 +1076,7 @@ static int validate_avrules(sepol_handle_t *handle, const avrule_t *avrule, int
 
 		switch(avrule->flags) {
 		case 0:
+			break;
 		case RULE_SELF:
 			if (p->policyvers != POLICY_KERN &&
 			    p->policyvers < MOD_POLICYDB_VERSION_SELF_TYPETRANS &&