Make mysqli_connect arguments explicitly nullable

It should be possible to skip any of these (and use the ini configured
defaults) by passing null, independently of strict_types settings.

Noticed while working on GH-4227.

Author: nikic

ext/mysqli/mysqli_nonapi.c

@@ -58,6 +58,7 @@ void mysqli_common_connect(INTERNAL_FUNCTION_PARAMETERS, zend_bool is_real_conne
 	size_t					hostname_len = 0, username_len = 0, passwd_len = 0, dbname_len = 0, socket_len = 0;
 	zend_bool			persistent = FALSE;
 	zend_long				port = 0, flags = 0;
+	zend_bool port_is_null = 1;
 	zend_string			*hash_key = NULL;
 	zend_bool			new_connection = FALSE;
 	zend_resource		*le;
@@ -80,8 +81,8 @@ void mysqli_common_connect(INTERNAL_FUNCTION_PARAMETERS, zend_bool is_real_conne
 	hostname = username = dbname = passwd = socket = NULL;
 
 	if (!is_real_connect) {
-		if (zend_parse_parameters(ZEND_NUM_ARGS(), "|ssssls", &hostname, &hostname_len, &username, &username_len,
-									&passwd, &passwd_len, &dbname, &dbname_len, &port, &socket, &socket_len) == FAILURE) {
+		if (zend_parse_parameters(ZEND_NUM_ARGS(), "|s!s!s!s!l!s!", &hostname, &hostname_len, &username, &username_len,
+				&passwd, &passwd_len, &dbname, &dbname_len, &port, &port_is_null, &socket, &socket_len) == FAILURE) {
 			return;
 		}
 
@@ -98,9 +99,8 @@ void mysqli_common_connect(INTERNAL_FUNCTION_PARAMETERS, zend_bool is_real_conne
 		flags |= CLIENT_MULTI_RESULTS; /* needed for mysql_multi_query() */
 	} else {
 		/* We have flags too */
-		if (zend_parse_method_parameters(ZEND_NUM_ARGS(), getThis(), "O|sssslsl", &object, mysqli_link_class_entry,
-										&hostname, &hostname_len, &username, &username_len, &passwd, &passwd_len, &dbname, &dbname_len, &port, &socket, &socket_len,
-										&flags) == FAILURE) {
+		if (zend_parse_method_parameters(ZEND_NUM_ARGS(), getThis(), "O|s!s!s!s!l!s!l", &object, mysqli_link_class_entry,
+				&hostname, &hostname_len, &username, &username_len, &passwd, &passwd_len, &dbname, &dbname_len, &port, &port_is_null, &socket, &socket_len, &flags) == FAILURE) {
 			return;
 		}
 
@@ -121,7 +121,7 @@ void mysqli_common_connect(INTERNAL_FUNCTION_PARAMETERS, zend_bool is_real_conne
 	if (!socket_len || !socket) {
 		socket = MyG(default_socket);
 	}
-	if (!port){
+	if (port_is_null || !port) {
 		port = MyG(default_port);
 	}
 	if (!passwd) {