The best-effort memory cleaning logic for MasterSecrets
is no longer accurate, since they are being passed through
both Binder calls as well as Intents, blurring whether an
activity is using a MasterSecret which is a reference to
shared memory in the KeyCachingService or not.
The 1.X Android versions don't have the 2.X VERSION_CODE
symbols, so comparing against them in order to make 1.6
choices will throw runtime exceptions.
