[Maria-developers] Please review: MDEV-8433 Make field<'broken-string' use indexes

Hi Sergei, Please review my patch for MDEV-8433. I had doubts about one detail: how to make Field::store() that we're currently creating a value for range search rather than regular doing a INSERT/UPDATE. I could think of two options: 1. Using sql_mode, similar to how temporal types pass MODE_INVALID_DATES. 2. Using a new parameter to this method: int Field::store(const char *str, uint length, CHARSET_INFO *cs); The former needed less changes, so I chose to use sql_mode. But probably N2 would be better. Please suggest. Thanks.