message: Fix algorithm selection in bench_ecmult
  Summary: This is a packport of secp256k1's PR509
  Test Plan:
  make check
  Reviewers: #bitcoin_abc, Fabien
diff: @@ -139,6 +139,7 @@ int main(int argc, char **argv) {
  secp256k1_gej* pubkeys_gej;
  size_t scratch_size;
  + data.ecmult_multi = secp256k1_ecmult_multi_var;
  if (argc > 1) {
  if(have_flag(argc, argv, "pippenger_wnaf")) {
  printf("Using pippenger_wnaf:\n");
  @@ -146,9 +147,11 @@ int main(int argc, char **argv) {
  } else if(have_flag(argc, argv, "strauss_wnaf")) {
  printf("Using strauss_wnaf:\n");
  data.ecmult_multi = secp256k1_ecmult_strauss_batch_single;
  - }
  } else {
  - data.ecmult_multi = secp256k1_ecmult_multi_var;
  + fprintf(stderr, "%s: unrecognized argument '%s'.\n", argv[0], argv[1]);
  + fprintf(stderr, "Use 'pippenger_wnaf', 'strauss_wnaf' or no argument to benchmark a combined algorithm.\n");
  + return 1;
  + }
  }
  /* Allocate stuff */
  