The WL enables support for long hostnames, with maximum of 255
characters.

There are several areas in MySQL that are changed. Following are
the details:

SERVER:
  * The following Dictionary columns are changed to use 288 char.
    definer is of the form <user_name>@<host_name> (32+1+255).

    mysql.servers.Host
    mysql.tables.definer
    mysql.events.definer
    mysql.routines.definer
    mysql.triggers.definer

    - DD version is increased due to above change.

  * The following INFORMATION_SCHEMA (I_S) table column size are increased
    to accomodate long hostname,

    I_S.USER_PRIVILEGES.GRANTEE
    I_S.SCHEMA_PRIVILEGE.GRANTEE
    I_S.TABLE_PRIVILEGE.GRANTEE
    I_S.COLUMN_PRIVILEGE.GRANTEE
    I_S.PROCESSLIST.Host
    I_S.CONNECTION_CONTROL_FAILED_ATTEMPTS.USERHOST

  * Changes to macros/constants:

    - Increase value of HOSTNAME_LENGTH from 60 to 255.
    - Removed MAX_HOSTNAME and used HOSTNAME_LENGTH instead.
    - Removed LIST_PROCESS_HOST_LEN and used HOSTNAME_LENGTH instead.

  * Temporary file creation to check for file system sensitivity
    now uses a predefined filename instead of using hostname in
    the file name. This avoids failure due to OS max file name
    limit of 255 char.

  * Error messages that display host names are changed to use
    %255s specifier instead of %64s.

ACL:
  * The following ACL columns are changed to use 255 char.
    mysql.db.Host
    mysql.user.Host
    mysql.default_roles.HOST
    mysql.default_roles.DEFAULT_ROLE_HOST
    mysql.role_edges.FROM_HOST
    mysql.role_edges.TO_HOST
    mysql.global_grants.HOST
    mysql.password_history.HOST
    mysql.tables_priv.Host
    mysql.columns_priv.Host
    mysql.procs_priv.Host
    mysql.proxies_priv.Host
    mysql.proxies_priv.Proxied_host

  * The following ACL columns are changed to use 288 char.
    Grantor is of the form <user_name>@<host_name> (32+1+255).

    mysql.proxies_priv.Grantor
    mysql.procs_priv.Grantor
    mysql.tables_priv.Grantor

  * scripts/mysql_system_tables.sql is modified to increase the
    length of host name columns in of ACL dictionary tables.

  * scripts/mysql_system_tables_fix.sql is modified to fix the
    ACL table hostname columns to use new host name length upon
    a upgrade.

  * The hardcoded ACL table definitions in source are modified
    to use long hostname in there definitions. These definitions
    are used to check if ACL table definition is not corrupt.

  * The SHOW CREATE USER command buffer length is changed. This
    fixed a windows issue, where it attempts to use more bytes
    than allocated.

PERFORMANCE SCHEMA:
  * Performance schema table columns which stores hostnames are
    modified to store 255 characters.

  * Performance schema version is changed, so that the upgrade
    re-creates the schema definitions.

  * The constant PSI_HOSTNAME_LENGTH is increased to 255.

SYS SCHEMA:
  * sys.ps_is_account_enabled function parameter 'in_host' is
    changed to use 255 character.

  * sys.version is modified incrementing the version, so that the
    sys schema is re-created upon upgrade.

  * sys.ps_setup_save uses "CREATE TABLE ... SELECT ... LIMIT 0", instead
    of "CREATE TABLE ... LIKE ..." to force use of InnoDB engine for
    temporary table instead of MyISAM. This is required to avoid max key
    length issue in MyISAM.

AUDIT_LOG_FILTER:

  * mysql.audit_log_user.HOST column length is increased to 255.

REPLICATION:
  * Binlog event size takes the new length of hostname into account.

  * Implementation of SHOW SLAVE HOSTS command is changed to use
    long hostname.

  * mysql.slave_master_info.Host

TESTS:
  We use debug variable to fake hostname within the server for testing.

  * main.hostname_length - Test ACL, DD, I_S
  * perfschema.hostname_length - Test P_S
  * rpl.rpl_long_invoker_hostname - Test long hostname in event long.
  * main.mysqlpump_long_hostname - Test mysqlpump and restore the schema.
  * main.mysql_80_inplace_upgrade is modified to use --skip-grant-tables
    options with --upgrade=MINIMAL option. This is required if ACL tables
    need upgrade.
  * rpl.rpl_long_invoker_hostname - Test invoker with long hostname.
  * rpl.rpl_lengthy_hostname - Basic replication using long report hostname.
  * rpl.gr_member_lengthy_hostname - Basic GR setup and PS tables.
  * connection_control.connection_control_long_hostname.
  * audit_log.audit_log_filter_long_hostname

NDB:
  * Added a hostname check unit test in NdbTCP.cpp.

UPGRADE:
  * Due to "WL#12971: Make MySQL stop if it can't source the privilege
    tables" the upgrade MINIMAL mode would fail if we don't use
    --skip-grant-tables option and if ACL tables are modified in current
    mysql version to which we are upgrading. The test case
    mysql_80_inplace_upgrade is updated.

Change-Id: I9549c6ef188c107837b532c89fd4791e4557383d