AndroidKeyStore: enforce keys have no encoding

getFormat() and getEncoding() should return "null" for PrivateKey
instances from AndroidKeyStore infrastructure.

Bug: 12877721

(cherry picked from commit 779702053c155b1bb22d2102db5b79d64791e9f9)

Change-Id: I067172b864202e4fb2043e76ad51fc56af356da1
2 files changed