Apply base64 encoding to compilation output

In other places, the logs are nicely base64 encoded and the twig
template applies a base64 decoding
(`webapp/templates/jury/internal_error.html.twig`) to render the
judgehost logs. This seems to be missed on this place.

Fixes issue #2456.

Author: Kevinjil

webapp/src/Controller/API/JudgehostController.php

@@ -431,7 +431,7 @@ public function updateJudgingAction(
                             ->setJudging($judging)
                             ->setContest($judging->getContest())
                             ->setDescription('Compilation results are different for j' . $judging->getJudgingid())
-                            ->setJudgehostlog('New compilation output: ' . $output_compile)
+                            ->setJudgehostlog(base64_encode('New compilation output: ' . $output_compile))
                             ->setTime(Utils::now())
                             ->setDisabled($disabled);
                         $this->em->persist($error);