'-r scsiioctl': No debug output may appear or debug output may appear twice [regression]

[Christian Franke]

SCSI debug output is now provided by new function scsi_pass_through_yield_sense() and commented out (only) in os_linux.cpp, see r5337 and r5431.

As a consequence, no debug output appears on Linux if scsi_device::scsi_pass_through[_and_check]() is called directly. This is currently the case if any of -d sat, -d usb* or -d snt* is used.

Debug output may appear twice if scsi_pass_through_yield_sense() is called on other platforms.

[Christian Franke]

Missing debug output occurs only with -d scsi on Linux and there is an easy workaround:
use -r scsiioctl,[34] instead of -r scsiioctl,[12].

Debug output may occur twice in other cases only if -r scsiioctl,[34] is used.

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