[PATCH] Convert signal.h from __need macros to bits/types/ headers.

[Joseph Myers]

On Tue, 6 Dec 2016, Zack Weinberg wrote:

> -  if (dest == NULL || left == NULL || right == NULL)
> +  if (!dest || !left || !right)

glibc style avoids implicit boolean conversions, so prefers == NULL here 
and anywhere else in the patch making such a change.

https://sourceware.org/glibc/wiki/Style_and_Conventions#Boolean_Coercions

-- 
Joseph S. Myers
joseph@codesourcery.com