uac(k): use type to detect www/proxy_authenticate hdrs

- reported by Mangust (mangust2), SF.net #2897594

modules_k/uac/auth.c

@@ -232,9 +232,9 @@ static inline struct hdr_field *get_autenticate_hdr(struct sip_msg *rpl,
 	}
 	for( hdr=rpl->headers ; hdr ; hdr=hdr->next )
 	{
-		if ( hdr->type!=HDR_OTHER_T )
-			continue;
-		if (cmp_hdrname_str(&hdr->name, &hdr_name)==0)
+		if((rpl_code==WWW_AUTH_CODE && hdr->type==HDR_WWW_AUTHENTICATE_T)
+				|| (rpl_code==PROXY_AUTH_CODE
+					&& hdr->type==HDR_PROXY_AUTHENTICATE_T))
 			return hdr;
 	}