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 scope3;
extern(C) int printf(char*, ...);
void main()
{
    int i;
    while (i < 10) {
        scope(success) i++;
    }
    printf("%d\n", i);
}