* it isn't "pfs" function, don't call it Item_func_pfs,
don't use item_pfsfunc.*
* tests don't depend on performance schema, put in the main suite
* inherit from Item_str_ascii_func
* use connection collation, not utf8mb3_general_ci
* set result length in fix_length_and_dec
* do not set maybe_null
* use my_snprintf() where possible
* don't set m_value.ptr on every invocation
* update sys schema to use the format_pico_time()
* len must be size_t (compilation error on Windows)
* the correct function name for double->double is fabs()
* drop volatile hack
- Innodb is not always available, which means t is not always
possible to use innodb system variables, or innodb information schema
tables.
Thus creation of objects that use Innodb information_schema is enclosed
into BEGIN NOT ATOMIC blocks with dummy SQLEXCEPTION handler.
- sys_config table uses Aria, just like other system tables.
- several tables that exist in MySQL, do not exist in MariaDB
performance_schema.replication_applier_status, mysql.slave_master_info,
mysql.slave_relay_log_info
