Add --set-exit-code-on-problem option.

tools/patch_sdk.dart

Index: tools/patch_sdk.dart
diff --git a/tools/patch_sdk.dart b/tools/patch_sdk.dart
index e5d71883eb25bbe829d9ebe9aa0330aeb95b9ddc..cfc50f2c01f0da61007ee9cad8348de8f011ed8c 100644
--- a/tools/patch_sdk.dart
+++ b/tools/patch_sdk.dart
@@ -143,6 +143,7 @@ Future _main(List<String> argv) async {
     var program = await kernelForProgram(
         Uri.parse('dart:$vmserviceName'),
         new CompilerOptions()
+          ..setExitCodeOnProblem = true
           // TODO(sigmund): investigate. This should be outline, but it breaks
           // vm-debug tests. Issue #30111
           ..sdkSummary = platform
@@ -204,6 +205,7 @@ Future _main(List<String> argv) async {
 Future<List<Uri>> compilePlatform(Uri patchedSdk, Target target, Uri packages,
     Uri fullOutput, Uri outlineOutput) async {
   var options = new CompilerOptions()
+    ..setExitCodeOnProblem = true
     ..strongMode = false
     ..compileSdk = true
     ..sdkRoot = patchedSdk