Fix VarDecls for tuples. Closes #99. I've implemented it this way since it doesn't require any changes in the frontend. However, I think having TypeTuple expressed as LLVM struct types would make much more sense and open the door to tuple lvalues.

module mini.norun_debug12;

interface I
{
    int foo();
}

class C : I
{
    int i = 24;
    int foo()
    {
        return i;
    }
}

void main()
{
    scope c = new C;
    I i = c;

    int* fail;
    *fail = 0;
}