gpg: Handle critical marked 'Reason for Revocation'.

gpg: Handle critical marked 'Reason for Revocation'.

* g10/parse-packet.c (can_handle_critical): Add
SIGSUBPKT_REVOC_REASON.
--

Some software seems to mark that subpacket as criticial.  Although gpg
has no special treatment for a revocation reasons (except for
--list-packets) we can accept a criticial marked anyway.  There are no
mandatary rules specified on how to handle a revocation reason.

Signed-off-by: Werner Koch <wk@gnupg.org>
(cherry picked from commit 3f6d949011f485613bb4bd3e06a2643be79cce40)

Gbp-Pq: Name 0059-gpg-Handle-critical-marked-Reason-for-Revocation.patch