bdb: Add bdb_get_hash_by_index

bdb_get_hash_by_index returns a hash entry from a BDB using an index.
bdb_get_hash is also renamed to bdb_get_hash_by_type. bdb_get_hash
is deprecated. Callers are expected to call bdb_get_hash_by_index(buf, 0)
instead.

BUG=none
BRANCH=none
TEST=make runtests

Change-Id: Id99926123c0ac9094574eb057c63f79eceda2867
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/392947
Reviewed-by: Randall Spangler <rspangler@chromium.org>
4 files changed