Fixed bug MDEV-9628.
In the function create_key_parts_for_pseudo_indexes() the key part
structures of pseudo-indexes created for BLOB fields were set
incorrectly. Also the key parts for long fields must be 'truncated' up
to the maximum length acceptable for key parts.
Fixed bug MDEV-11096.
1. When min/max value is provided the null flag for it must be set to 0
in the bitmap Culumn_statistics::column_stat_nulls. 2. When the
calculation of the selectivity of the range condition over a column
requires min and max values for the column then we have to check that
these values are provided.