Added a switch to reject illegal values for PACK_KEYS.


mysql-test/r/myisam.result:
  Bug#10056 - PACK_KEYS option take values greater than 1 while creating table
  The test result.
mysql-test/t/myisam.test:
  Bug#10056 - PACK_KEYS option take values greater than 1 while creating table
  The test case.