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 bug74;

char[] sformat(char[] s, ...)
{
    TypeInfo[] ti = _arguments;
    void* args = _argptr;
    return "";
}

void main()
{
}