Add some alignment info where LLVM might otherwise be more pessimistic. In particular, %.nest_arg is always aligned even though it's bitcast from i8*. Pointers in vtables are also guaranteed to be stored at aligned addresses.

module enum3;

enum GE : ushort
{
    A,B,C
}

void main()
{
    GE e = GE.B;
    size_t s = GE.sizeof;
    assert(e == 1);
    assert(e.sizeof == s);
    assert(s == 2);
}