Don't run "flake8" via stdin

Summary: flake8 v2.2.3 (released Aug 25) broke this. Just drop the stdin stuff.

Test Plan: User confirmed in IRC that this resolves the issue.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D10358

src/lint/linter/ArcanistFlake8Linter.php

@@ -58,14 +58,6 @@ final class ArcanistFlake8Linter extends ArcanistExternalLinter {
     return pht('Install flake8 using `easy_install flake8`.');
   }
 
-  public function supportsReadDataFromStdin() {
-    return true;
-  }
-
-  public function getReadDataFromStdinFilename() {
-    return '-';
-  }
-
   public function shouldExpectCommandErrors() {
     return true;
   }