dirmngr: Retry another server from the pool on 502, 503, 504.
* dirmngr/ks-engine-hkp.c (handle_send_request_error): Add arg http_status and handle it. (ks_hkp_search): Get http_status froms end_request and pass on to handle_send_request_error. (ks_hkp_get): Ditto. (ks_hkp_put): Ditto.
(cherry picked from commit 05ef6282784495a77f4faf76c0de5bc85dfecf06)
- GnuPG-bug-id: T4175
- Signed-off-by: Werner Koch <wk@gnupg.org>