Fix compiler warning discovered by clang-r484482

external/googletest/googletest/include/gtest/gtest.h:1545:11: error: invalid operands to binary expression ('const std::vector<unsigned char>' and 'const android::hardware::hidl_vec<unsigned char>') [clang-diagnostic-error]
  if (lhs == rhs) {
      ~~~ ^  ~~~

Test: presubmit
Change-Id: Iabe98a58d5dc5b9943c38240da2d8df6ac61fb7f