Hi,

according to the getopt(3) manpage (and to my testing) getopt returns 
'?' if an unknown option character is found and stores the insulting 
character in optopt.
This patch fixes the broken output in such a situation:

root@dosorca:/data/images# xl vcpu-list -j
option `?' not supported.
Name                  ID  VCPU   CPU State   Time(s) CPU Affinity
Domain-0               0     0    0   -b-     193.1  any cpu

turns into:

root@dosorca:/data/images# xl vcpu-list -j
option `j' not supported.
Name                  ID  VCPU   CPU State   Time(s) CPU Affinity
Domain-0               0     0    0   -b-     193.1  any cpu

Please apply to 4.1.0-rc.

By the way: some command parsers totally omit the faulting character and 
just output "option not supported."
Would you still accept a patch which turns all of those occurrences into 
the upper, more verbose form?
Especially as those conditions are not considered fatal and the command 
execution continues anyway, I found it rather confusing to read an 
unspecific error message without giving me a clue what I did wrong.

Regards,
Andre.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>

-- 
Andre Przywara
AMD-Operating System Research Center (OSRC), Dresden, Germany