minor symfony#26465 Default deleteFileAfterSend() to true (nowendwell)

This PR was merged into the 4.1-dev branch.

Discussion
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Default deleteFileAfterSend() to true

This should default to true when called since there is only one option.

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | N/A
| Fixed tickets | N/A
| License       | MIT
| Doc PR        |

<!--
* Defaults deleteFileAfterSend() to true
-->

Commits
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1de6f73 Default deleteFileAfterSend() to true

Author: fabpot

src/Symfony/Component/HttpFoundation/BinaryFileResponse.php

@@ -350,7 +350,7 @@ public static function trustXSendfileTypeHeader()
      *
      * @return $this
      */
-    public function deleteFileAfterSend($shouldDelete)
+    public function deleteFileAfterSend($shouldDelete = true)
     {
         $this->deleteFileAfterSend = $shouldDelete;