[weston PATCH] conf: add K_OFF check in autoconf

[Ander Conselvan de Oliveira]

I was about to sent this as a comment in bugzilla. See below.

On 04/13/2012 11:53 AM, juan.j.zhao at linux.intel.com wrote:
> From: Juan Zhao<juan.j.zhao at linux.intel.com>
>
> weston tty need to use K_OFF which is added in the kernel on linux-2.6.39.
> add this check in the configure stage.
> Bug Fix for https://bugs.freedesktop.org/show_bug.cgi?id=48579

I discussed this problem with Kristian on IRC on Wed. We don't need to 
change configure. Just protect the K_OFF code with an #ifdef and 
fallback to K_RAW in case it is not defined or the ioctl fails. In the 
fallback case, we also need to restore the on_tty_input() function for 
discarding the data on the tty.

Cheers,
Ander