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 condexp;

int f()
{
    return 42;
}

void main()
{
    int i = f() < 25 ? -1 : 1;
    /*int j = f() > 25 ? 1 : -1;
    assert(i);
    assert(!j);*/
}