Fix implicit fallthrough in arc

Summary: Raised by new linter.

Test Plan: Lint/inspection.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1831

src/lint/linter/xhpast/ArcanistXHPASTLinter.php

@@ -1460,6 +1460,7 @@ final class ArcanistXHPASTLinter extends ArcanistLinter {
 
           default:
             $key = null;
+            break;
         }
 
         if ($key !== null) {

src/parser/diff/ArcanistDiffParser.php

@@ -305,6 +305,7 @@ final class ArcanistDiffParser {
           break;
         default:
           $this->didFailParse("Unknown diff type.");
+          break;
       }
     } while ($this->getLine() !== null);