Currently InnoDB uses internal parser for adding foreign keys. Remove
internal parser and use data parsed by SQL parser (sql_yacc) for
adding foreign keys.
- create_table_info_t::create_foreign_keys() replacement for
dict_create_foreign_constraints_low();
- Pass constraint name via Foreign_key object.
Temporary until MDEV-20865:
- Pass alter_info as part of create_info.
There is several different ways to incorrectly define
foreign key constraint. In many cases earlier MariaDB
versions the error messages produced by these cases
are not very clear and helpful. This patch improves
the warning messages produced by foreign key parsing.
