nptl: fix libc sigaction signal checking

[Austin Foxley]

On 04/15/2010 06:54 AM, Timo Teräs wrote:
> We should not check for SIGCANCEL in __libc_sigaction because nptl calls
> this
> function to setup this signal. Nptl provides it's own override for
> sigaction
> that checks that the user cannot override signals nptl uses internally.
> Linuxthreads does not use SIGCANCEL at all so this affects nptl only.
> 
> Signed-off-by: Timo Teräs <timo.teras at iki.fi>

Thanks, applied.

-Austin