added new function test_if_data_home_dir() which checks that
path does not contain mysql data home directory.
Using of 'mysql data home'/'any db name' in
DATA DIRECTORY & INDEX DIRECTORY is disallowed


mysql-test/r/partition.result:
  test result
mysql-test/r/partition_not_windows.result:
  result fix
mysql-test/r/partition_symlink.result:
  result fix
mysql-test/r/symlink.result:
  test result update
mysql-test/t/partition.test:
  test case
mysql-test/t/partition_not_windows.test:
  test case update
mysql-test/t/partition_symlink.test:
  test case update
mysql-test/t/symlink.test:
  test case
sql/mysql_priv.h:
  new variable mysql_unpacked_real_data_home
sql/mysqld.cc:
  new variable mysql_unpacked_real_data_home
sql/partition_info.cc:
  new check_partition_dirs() which checks
  data directory and index directory for partition elements
sql/partition_info.h:
  new check_partition_dirs() which checks
  data directory and index directory for partition elements
sql/sql_parse.cc:
  added new function test_if_data_home_dir() which checks that
  path does not contain mysql data home directory.
  Using of 'mysql data home'/'any db name' in
  DATA DIRECTORY & INDEX DIRECTORY is disallowed