- Using DATA/INDEX DIRECTORY option on Windows put data/index file into
  default directory because the OS doesn't support readlink().
- The procedure for changing data/index file directory is 
  different under Windows.
- With this fix we report a warning if DATA/INDEX option is used,
  but OS doesn't support readlink().


mysql-test/r/windows.result:
  - updated result file.
mysql-test/t/windows.test:
  - Added test case to verify we get warnings if we specify DATA/INDEX
    DIRECTORY on a platform which doesn't support readlink().
sql/sql_parse.cc:
  - Added warnings if DATA/INDEX DIRECTORY option is used but not supported
    by the target platform.