message: gltfpack: Print command output in checkKtx/Basis
  When -vv command line argument is used we now don't suppress command
  output when testing the existence of toktx/basisu executables; this
  should help future diagnosis of issues around launching these easier.
diff: @@ -94,7 +94,7 @@ bool checkBasis(bool verbose)
  cmd += " -version";
  - int rc = execute(cmd.c_str(), /* ignore_stdout= */ true, /* ignore_stderr= */ true);
  + int rc = execute(cmd.c_str(), /* ignore_stdout= */ !verbose, /* ignore_stderr= */ !verbose);
  if (verbose)
  printf("%s => %d\n", cmd.c_str(), rc);
  @@ -165,7 +165,7 @@ bool checkKtx(bool verbose)
  cmd += " --version";
  - int rc = execute(cmd.c_str(), /* ignore_stdout= */ true, /* ignore_stderr= */ true);
  + int rc = execute(cmd.c_str(), /* ignore_stdout= */ !verbose, /* ignore_stderr= */ !verbose);
  if (verbose)
  printf("%s => %d\n", cmd.c_str(), rc);
  