sha1: fix context zeroing
sha1: fix context zeroing

trezor/trezor-crypto,romanz/trezor-crypto,runn1ng/trezor-crypto,runn1ng/trezor-crypto,trezor/trezor-crypto,romanz/trezor-crypto,runn1ng/trezor-crypto,jhoenicke/trezor-crypto,jhoenicke/trezor-crypto,trezor/trezor-crypto,runn1ng/trezor-crypto,romanz/trezor-crypto,runn1ng/trezor-crypto,romanz/trezor-crypto,trezor/trezor-crypto,trezor/trezor-crypto,jhoenicke/trezor-crypto,jhoenicke/trezor-crypto,romanz/trezor-crypto,jhoenicke/trezor-crypto