update the way of generating $fingerprint 

' array_to_newlines() ' , this function use a constant  ' PHP_EOL' .

```
define ('PHP_EOL', "\n");

function array_to_newlines(array $array)
{
    return implode(PHP_EOL, $array);
}

$build = array_to_newlines($assets->map(function($asset) { return $asset->build(true); })->all());

$fingerprint = $identifier.'-'.md5($build).'.'.$collection->getExtension($group);

```
Windows use '\n\r' to break line , and Linux,MacOS use '\n'.

So when I use the same code to build production in Windows and Linux(Mac) , I get two different $fingerprint and create two different build file.