Ensure the SignatureImpl overrides all methods

Since SignatureImpl's job is to select the correct SignatureSpi for a
given key type, it needs to have the chance to select it before it gets
to the actual delegated SignatureSpi.

One way to do that is simply to ensure that all methods are overridden
in the delegate. The base SignatureSpi overrides some of these by
calling over methods, but this may prevent us from enjoying some
optimizations that the real SignatureSpi provides.

Also, this seems to have prevented appRandom from being set correctly
on the delegated-to SignatureSpi and engineGetParameters() from ever
working correctly.

Bug: 22485587
Change-Id: I27a5bc58f74c37b07c0154e32df785e437596d2a
2 files changed