client_id->clientId, bugfix for signaling of read abort on stop.

- changed client_id->clientId, mClient_id->mClientId
- there was a bug in the condition for calling
  signalReadComplete_lock() in stop. We should call it only when
  !mLastReadCompleted and also if the current client has not already
  completed its read (this second check was missing before).

Change-Id: I9a57cf6b5c6f3260883a6c74d0c7b22f675c422e