Check both the function and the method via '@requires function' annotation

Make `@requires function ReflectionMethod::setAccessible` work according to the [documentation](http://phpunit.de/manual/4.1/en/incomplete-and-skipped-tests.html#incomplete-and-skipped-tests.skipping-tests-using-requires).
@rybakit That format only works for static methods. For example: http://3v4l.org/4T3ii

Here's the relevant section [from the docs](http://www.php.net/manual/en/language.types.callable.php#language.types.callable.passing):

> A method of an instantiated object is passed as an array containing an object at index 0 and the method name at index 1.
>
> Static class methods can also be passed without instantiating an object of that class by passing the class name instead of an object at index 0. As of PHP 5.2.3, it is also possible to pass 'ClassName::methodName'.