* configure.ac: Add option --default-trust-store.
(DEFAULT_TRUST_STORE_FILE): New ac_define.
* dirmngr/certcache.c: Include ksba-io-support.h.
(total_trusted_certificates, total_system_trusted_certificates): New.
(put_cert): Manage the new counters.
(cert_cache_deinit): Reset them.
(cert_cache_print_stats): Print them.
(is_trusted_cert): Add arg WITH_SYSTRUST. Change all callers to pass
false.
(load_certs_from_file): New.
(load_certs_from_system): New.
(cert_cache_init): Load system certificates.
--
Note that this code does not yet allow to load the system certificates
on Windows.
Signed-off-by: Werner Koch <wk@gnupg.org>