In case if we're dumping the peer which another
end belongs not to us but some other application
the attempts to flush data may lead to endless
SIGTTOU storm:

 | 1158  ioctl(53, TCFLSH, 0x2)            = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
 | 1158  --- SIGTTOU {si_signo=SIGTTOU, si_code=SI_KERNEL, si_value={int=5, ptr=0x5}} ---
 | 1158  --- stopped by SIGTTOU ---
 | 1158  ioctl(53, TCFLSH, 0x2)            = ? ERESTARTSYS (To be restarted if SA_RESTART is set)
 | 1158  --- SIGTTOU {si_signo=SIGTTOU, si_code=SI_KERNEL, si_value={int=5, ptr=0x5}} ---
 | 1158  --- stopped by SIGTTOU ---

so simply don't flush data, the initial attempt to use
TCIOFLUSH was rather "hey, we don't have a way to
say the kernel to freeze tty link for a while, lets
try to workaround this limitation" but without proper
kernel help this won't work anyway as Andrey has discovered.
Reported-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>