message: Fix unused-const-variable warning
diff: #include "caf/detail/fnv_hash.hpp"
  +#include <cstdint>
  +
  namespace caf {
  namespace detail {
  namespace {
  -template <size_t IntegerSize>
  -struct hash_conf_helper;
  +#if SIZE_MAX == 0xFFFFFFFF
  +
  +constexpr size_t basis = 2166136261u;
  +
  +constexpr size_t prime = 16777619u;
  +
  +#elif SIZE_MAX == 0xFFFFFFFFFFFFFFFF
  -template <>
  -struct hash_conf_helper<4> {
  - static constexpr size_t basis = 2166136261u;
  +constexpr size_t basis = 14695981039346656037u;
  - static constexpr size_t prime = 16777619u;
  -};
  +constexpr size_t prime = 1099511628211u;
  -template <>
  -struct hash_conf_helper<8> {
  - static constexpr size_t basis = 14695981039346656037u;
  +#else
  - static constexpr size_t prime = 1099511628211u;
  -};
  +# error Platform and/or compiler not supported
  -struct hash_conf : hash_conf_helper<sizeof(size_t)> {};
  +#endif
  } // namespace
  size_t fnv_hash(const unsigned char* first, const unsigned char* last) {
  - return fnv_hash_append(hash_conf::basis, first, last);
  + return fnv_hash_append(basis, first, last);
  }
  size_t fnv_hash_append(size_t intermediate, const unsigned char* first,
  const unsigned char* last) {
  auto result = intermediate;
  for (; first != last; ++first) {
  - result *= hash_conf::prime;
  + result *= prime;
  result ^= *first;
  }
  return result;
  