Compile with MySQL version >= 8.0.1

The my_bool type was removed with MySQL 8.0.1:
https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-1.html#mysqld-8-0-1-compiling

Replace my_bool with char which was the typedef in older MySQL versions
and still is in MariaDB.

[GB.DB.MYSQL]
* BUG: Compile with MySQL version >= 8.0.1.

gb.db.mysql/src/main.c

@@ -738,7 +738,7 @@ static int open_database(DB_DESC *desc, DB_DATABASE *db)
 	char *name;
 	char *host;
 	char *socket;
-	my_bool reconnect = TRUE;
+	char reconnect = TRUE;
 	unsigned int timeout;
 	char *env;
 	#if HAVE_MYSQL_SSL_MODE_DISABLED