g10: Don't cache search results if the search didn't scan the whole DB.
* g10/keydb.c (struct keydb_handle): Add new field is_reset. (keydb_new): Initialize hd->is_reset to 1. (keydb_locate_writable): Set hd->is_reset to 1. (keydb_search): Set hd->is_reset to 0. Don't cache a key not found if the search started from the beginning of the database.
- Signed-off-by: Neal H. Walfield <neal@g10code.com>.