mysql-test/mysql-test-run.pl:
  A fix (bug #12917: The --defaults-extra-file option is ignored by the 5.0 client binaries).
  MYSQL_MY_PRINT_DEFAULTS added
mysql-test/mysql-test-run.sh:
  A fix (bug #12917: The --defaults-extra-file option is ignored by the 5.0 client binaries).
  MYSQL_MY_PRINT_DEFAULTS added
mysys/default.c:
  A fix (bug #12917: The --defaults-extra-file option is ignored by the 5.0 client binaries).
  Set defaults_extra_file as we use it widely.