fix wccl-run iwth multiple output prionting when `aggregate' was off

wccl-apps/wccl-run.cpp

@@ -311,6 +311,7 @@ void Runner::run(boost::shared_ptr<Corpus2::TokenReader> reader, bool first)
 		}
 		if (!outputs.empty() && !aggregate_output_) {
 			output_tabular(outputs);
+			outputs.clear();
 		}
 		if (progress_) {
 			timer.check_slice();