ANDROID: binder: fix race in priority restore

During a reply, the target gets woken up and then the priority of the
replier is restored. The order is such to allow the target to process
the reply ASAP. Otherwise, we risk the sender getting scheduled out
before the wakeup happens. This strategy reduces transaction latency.

However, a subsequent transaction from the same target could be started
before the priority of the replier gets restored. At this point we save
the wrong priority and it gets reinstated at the end of the transaction.

This patch allows the incoming transaction to detect the race condition
and save the correct next priority. Additionally, the replier will abort
its pending priority restore which allows the new transaction to always
run at the desired priority.

Bug: 148101660
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Change-Id: I6fec41ae1a1342023f78212ab1f984e26f068221
(cherry picked from commit cac827f2619b280d418e546a09f25da600dafe5a)
[cmllamas: fixed trivial merge conflict]