- Update test to run properly on Windows.


mysql-test/t/sp-destruct.test:
  Bug#27144 sp-destruct.test is disabled on Windows
  - Enabled test on Windows.
  - Replaced non-portable system commands (mkdir, rmdir, mv, cp, echo) 
  with the mysqltest builtin commands.
  - Replace Windows directory seperator in error ER_NOT_FROM_FILE with
  posix directory seperator for single test/result pair.