Avoid deprecated sigblock in misc/tst-pselect.c

[Ondřej Bílka]

On Wed, Nov 26, 2014 at 04:57:12PM +0000, Joseph Myers wrote:
> misc/tst-pselect.c uses the deprecated sigblock interface, resulting
> in "tst-pselect.c:42:3: warning: 'sigblock' is deprecated (declared at
> ../signal/signal.h:189) [-Wdeprecated-declarations]".  The choice of
> sigblock rather than sigprocmask has nothing to do with what this test
> is testing, so this patch changes it to use sigprocmask to avoid the
> warning.
> 
> Tested for x86_64.
>
looks ok.