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_debug5;

void main()
{
    int i = 32;
    real r = 3.1415;
    real* p = &r;
    func(i,r,p);
}

void func(int i, real r, real* p)
{
    int* fail;
    *fail = 666;
}