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 bug15;

bool bool1(bool b) {
    if (b) return true;
    else return false;
}

bool bool2(bool b) {
    if (b) {return true;}
    else {return false;}
}

void main()
{
    assert(bool1(true));
    assert(!bool2(false));
}