Merge branch 'hi/gpg-use-check-signature'

Hide lower-level verify_signed-buffer() API as a pure helper to
implement the public check_signature() function, in order to
encourage new callers to use the correct and more strict
validation.

* hi/gpg-use-check-signature:
  gpg-interface: prefer check_signature() for GPG verification

diff --cc builtin/fmt-merge-msg.c
Simple merge

diff --cc log-tree.c
Simple merge