db_mysql: Drop usage of MYSQL_OPT_RECONNECT in 8.0.35+

The auto-reconnect feature of libmysqlclient has been deprecated
starting with version 8.0.34 and is subject to future removal.
Moreover, OpenSIPS was explicitly disabling it anyway on startup, in
favour of the "max_db_queries" application-level query retrying loop.

modules/db_mysql/my_con.c

@@ -57,7 +57,6 @@ int db_mysql_connect(struct my_con* ptr)
 {
 	str *tls_domain_name;
 
-	my_bool reconnect = 0;
 	/* if connection already in use, close it first*/
 	if (ptr->init)
 		mysql_close(ptr->con);
@@ -95,11 +94,14 @@ int db_mysql_connect(struct my_con* ptr)
 	mysql_options(ptr->con, MYSQL_OPT_READ_TIMEOUT, (void *)&db_mysql_timeout_interval);
 	mysql_options(ptr->con, MYSQL_OPT_WRITE_TIMEOUT, (void *)&db_mysql_timeout_interval);
 
-	/* force no auto reconnection */
-#if MYSQL_VERSION_ID >= 50013
-	mysql_options(ptr->con, MYSQL_OPT_RECONNECT, &reconnect);
-#else
+	/* explicitly disable auto-reconnect on older libraries (default: 0) */
+#if MYSQL_VERSION_ID < 50013
 	ptr->con->reconnect = 0;
+#elif MYSQL_VERSION_ID < 80034
+	{
+		my_bool reconnect = 0;
+		mysql_options(ptr->con, MYSQL_OPT_RECONNECT, &reconnect);
+	}
 #endif
 
 	if (ptr->id->port) {