gpg: Only print out TOFU statistics for conflicts in interactive mode

* g10/tofu.c (get_trust): Add arguments POLICYP and CONFLICT_SETP.  If
they are not NULL, return the policy and conflict set (if there is
one), respectively.  Update callers.  If MAY_ASK is FALSE, don't print
out the statistics.
(tofu_register_encryption): If there is a conflict and we haven't yet
printed the statistics about the conflicting bindings, do so now.
(tofu_get_validity): Likewise.

Signed-off-by: Neal H. Walfield <neal@g10code.com>
GnuPG-bug-id: 2914
(cherry picked from commit 027b81b35fe36692005b8dba22d9eb2db05e8c80)

Gbp-Pq: Name 0022-gpg-Only-print-out-TOFU-statistics-for-conflicts-in-.patch