new function dns_rdataclass_ismeta

lib/dns/include/dns/rdata.h

@@ -431,7 +431,7 @@ void dns_rdata_freestruct(void *source);
 
 isc_boolean_t dns_rdatatype_ismeta(dns_rdatatype_t type);
 /*
- * Find out whether the rdata type 'type' is a meta type
+ * Find out whether the rdata type 'type' is a meta-type
  * like ANY or AXFR.
  *
  * Requires:
@@ -439,6 +439,16 @@ isc_boolean_t dns_rdatatype_ismeta(dns_rdatatype_t type);
  *
  */
 
+isc_boolean_t dns_rdataclass_ismeta(dns_rdataclass_t rdclass);
+/*
+ * Find out whether the rdata class 'rdclass' is a meta-class
+ * like ANY or NONE.
+ *
+ * Requires:
+ * 	'rdclass' is a valid rdata class.
+ *
+ */
+
 dns_result_t
 dns_rdata_additionaldata(dns_rdata_t *rdata, dns_additionaldatafunc_t add,
 			 void *arg);