Allow zero analyzer args in build mode.

pkg/analyzer_cli/lib/src/options.dart

Index: pkg/analyzer_cli/lib/src/options.dart
diff --git a/pkg/analyzer_cli/lib/src/options.dart b/pkg/analyzer_cli/lib/src/options.dart
index 3f26109e5dc6ab852debfab02c78d52ebe97ea26..ae8466cd017b5dd734fe94e5765d0e28a3b22268 100644
--- a/pkg/analyzer_cli/lib/src/options.dart
+++ b/pkg/analyzer_cli/lib/src/options.dart
@@ -508,7 +508,7 @@ class CommandLineOptions {
         exitHandler(0);
         return null; // Only reachable in testing.
       } else {
-        if (results.rest.isEmpty) {
+        if (results.rest.isEmpty && !results['build-mode']) {
           _showUsage(parser);
           exitHandler(15);
           return null; // Only reachable in testing.