MDEV-5998 MySQL Bug#11756966 - 48958: STORED PROCEDURES CAN BE LEVERAGED TO BYPASS DATABASE SECURITY

Merge from mysql-5.6:
revno: 3257
committer: Jon Olav Hauglid <jon.hauglid@oracle.com>
branch nick: mysql-trunk-bug11756966
timestamp: Thu 2011-07-14 09:32:01 +0200
message:
  Bug#11756966 - 48958: STORED PROCEDURES CAN BE LEVERAGED TO BYPASS
                 DATABASE SECURITY

  The problem was that CREATE PROCEDURE/FUCTION could be used to
  check the existence of databases for which the user had no
  privileges and therefore should not be allowed to see.

  The reason was that existence of a given database was checked
  before privileges. So trying to create a stored routine in
  a non-existent database would give a different error than trying
  to create a stored routine in a restricted database.

  This patch fixes the problem by changing the order of the checks
  for CREATE PROCEDURE/FUNCTION so that privileges are checked first.
  This means that trying to create a stored routine in a
  non-existent database and in a restricted database both will
  give ER_DBACCESS_DENIED_ERROR error.

  Test case added to grant.test.