Identified all test cases in the MySQL file subquery.inc that are
not present in MariaDB. This patch adds the test cases that are:
- not present in MySQL 5.5, and
- already fixed in MariaDB 5.3

The patch adds test cases for the following mysql-trunk bugs:
- Bug#12763207 - not a bug, mysql-trunk, added test case
- BUG#50257    - not a bug, mysql-trunk, added test case
- Bug 11765699 - not a bug, mysql-trunk, added test case
- BUG#12616253 - not a bug, mysql-trunk, added test case

The comparison was based on the following version of
  mysql-trunk:
  
  revno: 3350 [merge]
  committer: Marko Mäkelä <marko.makela@oracle.com>
  branch nick: mysql-trunk
  timestamp: Mon 2011-08-08 12:42:09 +0300
  message:
    Merge mysql-5.5 to mysql-trunk.