81c778e broke the PKCS#11 hcrypto backend broke for many cases as it did
not support cipherstate resetting. (Prior to 81c778e, which was to fix#194,
the PKCS#11 backend did not support cipherstate chaining across invocations.)
hcrypto backends that maintain cipherstate independently of the hcrypto
context IV field need to set EVP_CIPH_ALWAYS_CALL_INIT to avoid the two
diverging. Their init function should support resetting the cipherstate
independently of key scheduling.