binderRpcBenchmark: main return 0

This main definition was copied from BENCHMARK_MAIN:

    // Helper macro to create a main routine in a test that runs the benchmarks
    #define BENCHMARK_MAIN()                   \
      int main(int argc, char** argv) {        \
        ::benchmark::Initialize(&argc, argv);  \
        if (::benchmark::ReportUnrecognizedArguments(argc, argv)) return 1; \
        ::benchmark::RunSpecifiedBenchmarks(); \
      }                                        \
      int main(int, char**)

This was fixed upstream, but it is still not merged into the Android:
https://github.com/google/benchmark/commit/835951aa44c2f802b4d563d533eac34565848eb0

Bug: N/A
Test: binderRpcBenchmark returns success error code
Change-Id: Icd9f32c234500abd582f1cce7d0025e234943c17