Refuse to reuse IV in encryption mode in AndroidKeyStore.

This makes IV-using Cipher implementations backed by AndroidKeyStore
refuse to be reused. After Cipher.doFinal completes, invoking update
or doFinal will raise an exception. This is to make it harder to
violate the security best practice of not reusing IV in encryption
mode.

Bug: 18088752
Change-Id: I5102f9e8b2ff428254294703e48948ea8576603d