message: [C++] Changes in the flathash program
  * Correct the usage in the flathash program
  As it is possible to have -- before the occurrence of the first
  input STRING.
  * Exit with 1 in the flathash program when an error occurs
diff: @@ -25,7 +25,7 @@ enum OutputFormat { kDecimal, kHexadecimal, kHexadecimal0x };
  int main(int argc, char *argv[]) {
  const char *name = argv[0];
  if (argc <= 1) {
  - printf("%s HASH [OPTION]... STRING... [-- STRING...]\n", name);
  + printf("%s HASH [OPTION]... [--] STRING...\n", name);
  printf("Available hashing algorithms:\n");
  printf(" 16 bit:\n");
  size_t size = sizeof(flatbuffers::kHashFunctions16) /
  @@ -50,7 +50,7 @@ int main(int argc, char *argv[]) {
  " -x Output hash in hexadecimal.\n"
  " -0x Output hash in hexadecimal and prefix with 0x.\n"
  " -c Append the string to the output in a c-style comment.\n");
  - return 0;
  + return 1;
  }
  const char *hash_algorithm = argv[1];
  @@ -64,7 +64,7 @@ int main(int argc, char *argv[]) {
  if (!hash_function16 && !hash_function32 && !hash_function64) {
  printf("\"%s\" is not a known hash algorithm.\n", hash_algorithm);
  - return 0;
  + return 1;
  }
  OutputFormat output_format = kHexadecimal;
  