Fix array_map optimization with non-literal function or non-literal args

[arnaud-lb]

Non-literal expressions must be evaluated once and memoized to maintain semantics:

$callback = function ($value) {
    global $callback;
    $callback = function () { return 'changed'; };
    return $value + 1;
};

array_map($callback, [1,2]);

// Expected result: [2,3]
// Actual result: [2,'changed']

Unfortunately, we can't memoize pre-bound PFA arguments without breaking pass-by-reference, so we disable the optimization if the callback is a PFA with non-literal arguments. We could improve this when the function is known and we can determine that the argument is not passed by ref.

Bug found by Ryan @ Calif.io.