Function CastInts

cpp/src/arrow/util/int_util.h:77–80

template <typename InputInt, typename OutputInt>
inline typename std::enable_if<(sizeof(InputInt) >= sizeof(OutputInt))>::type CastInts(
    const InputInt* source, OutputInt* dest, int64_t length) {
  DowncastInts(source, dest, length);
}

template <typename InputInt, typename OutputInt>
inline typename std::enable_if<(sizeof(InputInt) < sizeof(OutputInt))>::type CastInts(