Problem was that there are no support for symlinked files on Windows for
mysqld. So we fail when trying to create them.

Solution: Ignore the DATA/INDEX DIRECTORY clause for partitions and push
a warning. (Just like a MyISAM table)


mysql-test/r/partition.result:
  Bug#30459 Partitioning across disks failing on Windows
  Moved symlink specific tests to partition_symlink
  result file
mysql-test/r/partition_symlink.result:
  Bug#30459 Partitioning across disks failing on Windows
  Moved symlink specific tests from partition.test
  result file
mysql-test/r/partition_windows.result:
  Bug#30459 Partitioning across disks failing on Windows
  result file
mysql-test/t/partition.test:
  Bug#30459 Partitioning across disks failing on Windows
  Moved symlink specific tests to partition_symlink
  test file
mysql-test/t/partition_symlink.test:
  Bug#30459 Partitioning across disks failing on Windows
  Moved symlink specific tests from partition.test
  test file
mysql-test/t/partition_windows.test:
  Bug#30459 Partitioning across disks failing on Windows
  test file