Major bugfixes:

- handle actual SCSI and ATA errors and not only ioctl() errors;
- use ATACMD_READREG I/O request flag if ATA command does not perform I/O and/or
  returns data in ATA registers;
- set up I/O request properly for AUTO_OFFLINE and AUTOSAVE commands (inspired by
  similar changes in os_freebsd.cpp);
- handle AUTO_OFFLINE and AUTOSAVE like STATUS_CHECK (like os_linux.cpp does).


git-svn-id: https://smartmontools.svn.sourceforge.net/svnroot/smartmontools/trunk@2466 4ea69e1a-61f1-4043-bf83-b5c94c648137