Update out-of-date API calls when rendering diffs inline in email

Summary: See PHI1745. This callsite for "ChangesetParser" was not properly updated for recent changes.

Test Plan:
  - Set `metamta.differential.inline-patches` to 100.
  - Created a new revision with a small (<100 line) diff, with at least one reviewer.
  - Ran `bin/phd debug` and observed outbound mail queue with `bin/mail list-outbound`.
  - Before: fatal when trying to generate the inline changes for mail.
  - After: clean mail generation.

Differential Revision: https://secure.phabricator.com/D21270

src/applications/differential/mail/DifferentialChangeDetailMailView.php

@@ -40,11 +40,13 @@ final class DifferentialChangeDetailMailView
     $diff = $this->getDiff();
 
     $engine = new PhabricatorMarkupEngine();
+    $viewstate = new PhabricatorChangesetViewState();
 
     $out = array();
     foreach ($diff->getChangesets() as $changeset) {
       $parser = id(new DifferentialChangesetParser())
-        ->setUser($viewer)
+        ->setViewer($viewer)
+        ->setViewState($viewstate)
         ->setChangeset($changeset)
         ->setLinesOfContext(2)
         ->setMarkupEngine($engine);