veyron2/ipc: ServerContext is no longer a context.T.
veyron2/ipc: ServerContext is no longer a context.T.

Change-Id: I78fb522bbaa74a772c99db98b2c989988c08936b
MultiPart: 1/2

vanadium/go.v23,vanadium/go.v23,vanadium/go.v23