Bump to Java.Interop/master/10647a5e (#1295)

Fixes the `ObjectDisposedException` during process shutdown described
in commit 0a9d164.

Moves the `ManagedPeer.Init()` invocation within the `JniRuntime`
constructor so that a `NullReferenceException` is avoided. (Instead, a
*different*, more meaningful exception should be thrown.)

Bumps to cecil/mono-2017-12/1afa0668 for d15-7 harmonization.