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 typeinfo7;
extern(C) int printf(char*, ...);
int func(long)
{
    return 0;
}

void main()
{
    auto ti = typeid(typeof(func));
    auto s = ti.toString;
    printf("%.*s\n", s.length, s.ptr);
    assert(s == "int()");
}