fix(previews): movie preview bug fix, in some case stream reading functions may block indefinitly

Signed-off-by: cn-shell <jpsn@foxmail.com>
Co-authored-by: Ferdinand Thiessen <opensource@fthiessen.de>

Author: jpsn123

lib/private/Preview/Movie.php

@@ -343,6 +343,8 @@ private function generateThumbNail(int $maxX, int $maxY, string $absPath, int $s
 		$returnCode = -1;
 		$output = '';
 		if (is_resource($proc)) {
+			stream_set_blocking($pipes[1], false);
+			stream_set_blocking($pipes[2], false);
 			// Read stderr before stdout: ffmpeg's stderr can exceed 64KB (OS pipe buffer) for certain
 			// files, causing a deadlock if stdout is read first. stdout is always empty.
 			$stderr = trim(stream_get_contents($pipes[2]));