REORG: server: Export and rename some functions updating server info

Some static functions are now exported and renamed to follow the same
pattern of other exported functions. Here is the list :

 * update_server_fqdn: Renamed to srv_update_fqdn and exported
 * update_server_check_addr_port: renamed to srv_update_check_addr_port and exported
 * update_server_agent_addr_port: renamed to srv_update_agent_addr_port and exported
 * update_server_addr: renamed to srv_update_addr
 * update_server_addr_potr: renamed to srv_update_addr_port
 * srv_prepare_for_resolution: exported

This change is mandatory to move all functions dealing with the server-state
files in a separate file.
diff --git a/src/resolvers.c b/src/resolvers.c
index a268701..ab7159f 100644
--- a/src/resolvers.c
+++ b/src/resolvers.c
@@ -637,10 +637,10 @@
 
 					switch (item->ar_item->type) {
 						case DNS_RTYPE_A:
-							update_server_addr(srv, &(((struct sockaddr_in*)&item->ar_item->address)->sin_addr), AF_INET, "DNS additional record");
+							srv_update_addr(srv, &(((struct sockaddr_in*)&item->ar_item->address)->sin_addr), AF_INET, "DNS additional record");
 						break;
 						case DNS_RTYPE_AAAA:
-							update_server_addr(srv, &(((struct sockaddr_in6*)&item->ar_item->address)->sin6_addr), AF_INET6, "DNS additional record");
+							srv_update_addr(srv, &(((struct sockaddr_in6*)&item->ar_item->address)->sin6_addr), AF_INET6, "DNS additional record");
 						break;
 					}
 
@@ -656,7 +656,7 @@
 						HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
 						continue;
 					}
-					msg = update_server_fqdn(srv, hostname, "SRV record", 1);
+					msg = srv_update_fqdn(srv, hostname, "SRV record", 1);
 					if (msg)
 						send_log(srv->proxy, LOG_NOTICE, "%s", msg);
 				}