MDEV-11952 Oracle-style packages: stage#5

- CREATE PACKAGE [BODY] statements are now
  entirely written to mysql.proc with type='PACKAGE' and type='PACKAGE BODY'.
- CREATE PACKAGE BODY now supports IF NOT EXISTS
- DROP PACKAGE BODY now supports IF EXISTS
- CREATE OR REPLACE PACKAGE [BODY] is now supported
- CREATE PACKAGE [BODY] now support the DEFINER clause:

    CREATE DEFINER user@host PACKAGE pkg ... END;
    CREATE DEFINER user@host PACKAGE BODY pkg ... END;

- CREATE PACKAGE [BODY] now supports SQL SECURITY and COMMENT clauses, e.g.:

    CREATE PACKAGE p1 SQL SECURITY INVOKER COMMENT "comment" AS ... END;

- Package routines are now created from the package CREATE PACKAGE BODY
  statement and don't produce individual records in mysql.proc.

- CREATE PACKAGE BODY now supports package-wide variables.
  Package variables can be read and set inside package routines.
  Package variables are stored in a separate sp_rcontext,
  which is cached in THD on the first packate routine call.

- CREATE PACKAGE BODY now supports the initialization section.

- All public routines (i.e. declared in CREATE PACKAGE)
  must have implementations in CREATE PACKAGE BODY

- Only public package routines are available outside of the package

- {CREATE|DROP} PACKAGE [BODY] now respects CREATE ROUTINE and ALTER ROUTINE
  privileges

- "GRANT EXECUTE ON PACKAGE BODY pkg" is now supported

- SHOW CREATE PACKAGE [BODY] is now supported

- SHOW PACKAGE [BODY] STATUS is now supported

- CREATE and DROP for PACKAGE [BODY] now works for non-current databases

- mysqldump now supports packages

- "SHOW {PROCEDURE|FUNCTION) CODE pkg.routine" now works for package routines

- "SHOW PACKAGE BODY CODE pkg" now works (the package initialization section)

- A new package body level MDL was added

- Recursive calls for package procedures are now possible

- Routine forward declarations in CREATE PACKATE BODY are now supported.

- Package body variables now work as SP OUT parameters

- Package body variables now work as SELECT INTO targets

- Package body variables now support ROW, %ROWTYPE, %TYPE

sql/sql_show.h

@@ -106,7 +106,7 @@ bool mysqld_show_contributors(THD *thd);
 bool mysqld_show_privileges(THD *thd);
 char *make_backup_log_name(char *buff, const char *name, const char* log_ext);
 uint calc_sum_of_all_status(STATUS_VAR *to);
-void append_definer(THD *thd, String *buffer, const LEX_CSTRING *definer_user,
+bool append_definer(THD *thd, String *buffer, const LEX_CSTRING *definer_user,
                     const LEX_CSTRING *definer_host);
 int add_status_vars(SHOW_VAR *list);
 void remove_status_vars(SHOW_VAR *list);