I (nckx) have revoked all RSA subkeys, in favour of my older and
freshly-refreshed ECDSA ones. This was merely a precaution: to my
knowledge all my RSA private keys have been carefully destroyed and
were never compromised. This commit keeps ‘make authenticate’ happy.
* guix/gnupg.scm (revkeysig-rx): New variable for revoked keys.
(gnupg-verify): Parse it.
(gnupg-status-good-signature?): Accept it as ‘good’ for our purposes.
* build-aux/git-authenticate.scm (%committers): Clarify nckx's subkeys.
Signed-off-by: Ludovic Courtès <firstname.lastname@example.org>