Allow multiple inputs to compare-failures

tools/gardening/bin/compare_failures.dart

Index: tools/gardening/bin/compare_failures.dart
diff --git a/tools/gardening/bin/compare_failures.dart b/tools/gardening/bin/compare_failures.dart
index 67f39db33493887731faaf9f30af4b6d4ccc01a6..f679775375da15de51bd07b454d22a10f85b5dd5 100644
--- a/tools/gardening/bin/compare_failures.dart
+++ b/tools/gardening/bin/compare_failures.dart
@@ -35,7 +35,7 @@ main(List<String> args) async {
 
   var runCount = int.parse(argResults['run-count'], onError: (_) => null);
 
-  if (argResults.rest.length != 1 || argResults['help'] || runCount == null) {
+  if (argResults.rest.length < 1 || argResults['help'] || runCount == null) {
     help(argParser);
     if (argResults['help']) return;
     exit(1);