Do not stick to the last used server address when a new DNS lookup is done, REF 15378

The previous solution for sticking to the last used server address was implemented in f2ba4af0 and came from iowrt. Our requirement is to try to switch to the primary server at each new DNS lookup, hoping that the server has recovered from being offline.

res/res_pjsip/pjsip_resolver.c

@@ -162,48 +162,6 @@ static int pjsip_server_addresses_cmp(pjsip_server_addresses *addr1, pjsip_serve
 	return 0;
 }
 
-/*! \brief update the tracked pjsip_server_addresses with new resolve
- *  Note: The tracked and new resolved server addresses must same, but maybe in different order.
- *  The order of resolved addresses may be round-shifted, to make the current using server address
- *  always be the first entry.
- */
-static void pjsip_server_addresses_track_update(struct host_track_entry *host, pjsip_server_addresses *addrs)
-{
-	int c, i;
-	char buffer[512];
-
-	// Get the index of current server address in the new address table
-	for (c = 0; c < addrs->count; c++) {
-		if (!pjsip_server_addresses_entry_cmp(&host->addresses, host->cur_addr, addrs, c))
-			break;
-	}
-
-	// The current server address is the first entry in the new table
-	if (c == 0) {
-		pj_memcpy(&host->addresses, addrs, sizeof(*addrs));
-		host->cur_addr = 0;
-		pj_sockaddr_print(&host->addresses.entry[0].addr, buffer, sizeof(buffer), 3);
-
-		for (i = 0; i < addrs->count; i++) {
-			pj_sockaddr_print(&host->addresses.entry[i].addr, buffer, sizeof(buffer), 3);
-			ast_debug(5, "host track '%s': address[%d] = '%s'\n", host->target.host, i, buffer);
-		}
-		return;
-	}
-
-	// Re-order the new table, to make sure the current server address is the first entry
-	for (i = 0; i < addrs->count; i++) {
-		pj_memcpy(&host->addresses.entry[i], &addrs->entry[c], sizeof(addrs->entry[0]));
-		if (++c >= addrs->count)
-			c = 0;
-
-		pj_sockaddr_print(&host->addresses.entry[i].addr, buffer, sizeof(buffer), 3);
-		ast_debug(5, "host track '%s': address[%d] = '%s'\n", host->target.host, i, buffer);
-	}
-	pj_memcpy(addrs, &host->addresses, sizeof(*addrs));
-	host->cur_addr = 0;
-}
-
 static pjsip_server_addresses *get_cached_host_addrs(const pjsip_host_info *target)
 {
 	pjsip_server_addresses *cached_addrs = NULL;
@@ -279,8 +237,8 @@ static void sip_resolve_target_track(struct sip_resolve *resolve)
 				break;
 			}
 
-			// The new addresses are same as tracked, but maybe in different order
-			pjsip_server_addresses_track_update(host, addresses);
+			pj_memcpy(&host->addresses, addresses, sizeof(*addresses));
+			host->cur_addr = 0;
 
 			host->expiry = resolve->ttl + time(NULL);
 			ast_debug(5, "host track '%s' (%s): record updated, to be expired at %s\n", host->target.host,