kbx: Add function keybox_tmp_names to avoid code duplication.
* kbx/keybox-update.c (create_tmp_file): Move some code to... * kbx/keybox-util.c (keybox_tmp_names): new. * g10/keyring.c: Include keybox.h. (create_tmp_file): Replace parts by keybox_tmp_names.
- Signed-off-by: Werner Koch <wk@gnupg.org>