gnupg: security bump to version 1.4.22

Mitigate a flush+reload side-channel attack on RSA secret keys
dubbed "Sliding right into disaster".  For details see
<https://eprint.iacr.org/2017/627

>.  [CVE-2017-7526]

Switch to https site for better firewall compatibility and security.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>