We're seeing the warning:
WARNING: QA Issue: xserver-xorg rdepends on nettle but its not a build dependency? [build-deps]
We list openssl in DEPENDS so we need to specify that as the sha1 provider
rather that nettle which is autodetected.
(From OE-Core rev: bfc19d81a5992c8b7b725a873dda527c9c9c148d)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>