[Maria-developers] MDEV-8214 Asian MB2 charsets: compare broken bytes as "greater than any non-broken character"

Hi Sergei, For simplicity I decided to split: MDEV-8036 Fix all collations to compare broken bytes as "greater than any non-broken character" into sub-tasks. Please review a patch for the first sub-task MDEV-8214. The overall plan is: - MDEV-8214, for the Asian charsets with mbmaxlen=2 - MDEV-8215, for the Asian charsets with mbmaxlen=3, based on MDEV-8214 - MDEV-8036, the rest (Unicode character sets) Thanks.