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 pointers;

struct S
{
    long l;
}

void main()
{
    int j = 42;
    int* p = &j;

    auto t = *p;
    *p ^= t;

    *p = ~t;

    S s;
    S* sp = &s;
    *sp = s;
    s = *sp;
}