Backporting a part of MDEV-32026 (which also fixed MDEV-32025 in 11.3)
from 11.3 to 10.4.
The reported crash happened with --lower-case-table-names=2
on statements like:
ALTER DATABASE Db1 DEFAULT CHARACTER SET utf8;
ALTER DATABASE `#mysql50#D+b1` UPGRADE DATA DIRECTORY NAME;
lock_schema_name() expects a normalized database name
and assert if a non-normalized name comes.
mysql_alter_db_internal() and mysql_upgrade_db() get
a non-normalized database name in the parameter.
Fixing them to normalize the database name before passing
it to lock_schema_name().
lower_case_table_names=2 means "table names and database names are
stored as declared, but they are compared in lowercase".
But names of objects in grants are stored in lowercase for any value
of lower_case_table_names. This caused an error when checking grants
for objects containing uppercase letters since table_hash_search()
didn't take into account lower_case_table_names value
