tar --help is failing on Solaris.

[Karel Gardas]

Hello Mikhail,

you are the author of the patch eaf2aae18603965ff668384b391fcaa14de19823 
in libraries/Cabal which you have merged into GHC HEAD on September 25 
in the patch 4be50969491aa471d6c9ab3b9339036a355d45c6

The problem is that your patch breaks build on Solaris, here is the log 
from the Solaris/x86 builder:
http://haskell.inf.elte.hu/builders/solaris-x86-head/178/10.html

Could you be so kind and revert this patch or fix it to also work on 
Solaris? For Solaris the change should be easy, simply if you invoke 
Solaris' tar with --help, it'll fail with exit code 1 and help message 
printed into the stderr. If you are curious if it supports --format, 
then no.

Please let me know if you are able to push fix or revert during next 
week or if I shall deal with it myself. I can't just fix that now myself 
since I'm overloaded with other tasks till Wednesday night...

Thanks!
Karel