message: fuzz: FuzzedFileProvider::write should not return negative value
  Doing so can lead to a glibc crash. Also the manpage for fopencookie
  warns against this:
diff: @@ -566,7 +566,7 @@ ssize_t FuzzedFileProvider::write(void* cookie, const char* buf, size_t size)
  SetFuzzedErrNo(fuzzed_file->m_fuzzed_data_provider);
  const ssize_t n = fuzzed_file->m_fuzzed_data_provider.ConsumeIntegralInRange<ssize_t>(0, size);
  if (AdditionOverflow(fuzzed_file->m_offset, (int64_t)n)) {
  - return fuzzed_file->m_fuzzed_data_provider.ConsumeBool() ? 0 : -1;
  + return 0;
  }
  fuzzed_file->m_offset += n;
  return n;
  