message: fuzz: use nanoseconds for SystemTime in RequestInfo.
  Avoids integer overflow that was previously occurring due to time in micros being too large, allows
  exercise of nanosecond resolution formatters beyond all zero.
  Fixes oss-fuzz issue
  Risk level: Low
  Testing: Corpus entry added.
diff: @@ -36,7 +36,13 @@ inline test::fuzz::Headers toHeaders(const Http::HeaderMap& headers) {
  inline TestRequestInfo fromRequestInfo(const test::fuzz::RequestInfo& request_info) {
  TestRequestInfo test_request_info;
  test_request_info.metadata_ = request_info.dynamic_metadata();
  - test_request_info.start_time_ = SystemTime(std::chrono::microseconds(request_info.start_time()));
  +#ifdef __APPLE__
  + // Clocks don't track at nanosecond on OS X.
  + test_request_info.start_time_ =
  + SystemTime(std::chrono::microseconds(request_info.start_time() / 1000));
  +#else
  + test_request_info.start_time_ = SystemTime(std::chrono::nanoseconds(request_info.start_time()));
  +#endif
  if (request_info.has_response_code()) {
  test_request_info.response_code_ = request_info.response_code().value();
  }
  