ReflectionClass#isInstantiable() should report false for private constructors

[UFOMelkor]

Looks like the current implementation of isInstantiable is not compatible with the reflection extension:

<?php
declare(strict_types=1);
require_once __DIR__ . '/vendor/autoload.php';

use Roave\BetterReflection\BetterReflection;

class ClassWithPrivateConstructor
{
    private function __construct()
    {
    }
}

$betterReflector = (new BetterReflection())->classReflector();
var_dump((new ReflectionClass(ClassWithPrivateConstructor::class))->isInstantiable());
var_dump($betterReflector->reflect(ClassWithPrivateConstructor::class)->isInstantiable());

outputs

bool(false)
bool(true)

[kukulich]

Fixed in #412