Don't prompt for patches when outputting lint results as XML.

Summary: The Checkstyle XML output format is not intended to be an interactive workflow.

Test Plan: Introduced linter issues and ran `arc lint`. Verified that no interactive prompt was shown.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9107

src/workflow/ArcanistLintWorkflow.php

@@ -459,6 +459,8 @@ EOTEXT
         break;
       case 'xml':
         $renderer = new ArcanistLintCheckstyleXMLRenderer();
+        $prompt_patches = false;
+        $apply_patches = $this->getArgument('apply-patches');
         break;
       default:
         $renderer = new ArcanistLintConsoleRenderer();