Description:
------------
I just updated an application from PHP 5.6 to PHP 7.0 after carefully reading the upgrading guide and documentation, but I just ran into a bit of an issue.

We had code that was modifying values (via a value reference) in place when passed to an `array_filter()` call, to prevent us from having to run multiple loop iterations, but that doesn't seem to work in PHP 7.

While I understand that the runtime semantics may have changed for these functions, I can't find this behavior change to be documented anywhere, so I wasn't sure if it was intentional or not. I know that `foreach` has changed in PHP 7, which is relatively well documented, but these array function behavior changes don't seem to be.

I've tried to see if this behavior has changed in other array functions too, such as `array_reduce`, and the issue seems to exist there too. My guess is that this has to do with how values are passed/referenced in these functions under the new PHP 7 runtime/engine.

Test script:
---------------
/**
 * 3v4l.org URL: https://3v4l.org/bERrp
 */

$data = ['foo', 'bar'];

var_dump($data);

$filtered = array_filter($data, function (&$value) {
    $value = (bool) $value;
    
    return true;
});

var_dump($filtered);

Expected result:
----------------
array(2) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(3) "bar"
}
array(2) {
  [0]=>
  bool(true)
  [1]=>
  bool(true)
}

Actual result:
--------------
array(2) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(3) "bar"
}
array(2) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(3) "bar"
}