Ada bootstrap broken on x86 and x86_64

[Richard Kenner]

    I think the other catch is that the function is expected to remove one
    wrapper at a time.

That seems like a bad idea since it's incompatible with what everything else
in the compiler does and it's also not clear things could notice, but I agree
that the documentation of this function is less than clear.

    I think I will leave this problem to Zdenek unless it will appear to
    hit us somehow for now.  

Makes sense.