libbinder: RPC use 'status_t' over 'bool'

For ease of debugging/handling errors (I realized that binderRpcTest
currently crashes on Pixel 3 because of some missing kernel patches -
this would have been easier with this, and one potential (even if
temporary) solution would be to check the return code).

Bug: 167966510
Test: binderRpcTest, binderRpcBenchmark, binder_parcel_fuzzer,
    binder_rpc_fuzzer, binderHostDeviceTest
Change-Id: I1baa2e9380e0ec8f82f8ceb250f3eeb632dc5fbc