Unaligned block moves and MEM_ALIGN re-broken

[Richard Kenner]

    I am a little concerned what other problems are going to show up with
    this patch which now is going to make a lot of objects appear much
    less aligned.

I'm not.  On a non-STRICT_ALIGNMENT machine, alignment problems affect only
efficiency, not correctness.

    This patch needs to be thoroughly regression tested.

I was hoping you'd do that on an rs6000 target.