How to pass noncopyable variadic arguments with ref?

[tchaloupka]

Hi,
I've found strange behavior where:

```D
import std.stdio;

struct Foo
{
     @disable this(this);
     int x;
}

void test(Foo[] foos...)
{
     foreach (ref f; foos) {
         writeln(&f, ": ", f.x);
         f.x = 0;
     }
}

void main()
{
     Foo f1 = Foo(1);
     Foo f2 = Foo(2);
     writeln("f1: ", &f1);
     writeln("f2: ", &f2);
     test(f1, f2);
     writeln("f1: ", f1.x);
     writeln("f2: ", f2.x);
}
```

Compiles fine (no error on passing noncopyable arguments to the 
function), but there are other objects passed to the function as 
they aren't cleared out in the caller scope.

Shouldn't it at least protest that objects can't be passed to the 
function as they aren't copyable?