fix wcclrun stdin corpora reading

wcclrun/main.cpp

@@ -287,7 +287,7 @@ int main(int argc, char** argv)
 			operator_strings.push_back(f);
 		}
 	}
-	if (corpora_files.empty() || (operator_strings.empty() && !output_orths)) {
+	if ((corpora_files.empty() && !corpus_stdin) || (operator_strings.empty() && !output_orths)) {
 		std::cerr << "Nothing to do, try " << argv[0] << " -h\n";
 		return 2;
 	}