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.ptrcond;

void main()
{
    char[4]* cp;
    void* vp = &cp;
    assert(cp < vp);
}