libbinder: Return status_t from RpcTransport::peek()

Result<> pulls in over 100k of extra libc++ code on Trusty
so this CL replaces it with status_t as the result type of
RpcTransport::peek().

Bug: 224644083
Test: atest binderRpcTest
Change-Id: Idde111245794dc4afd421f3a723feacc8c3a346e
5 files changed