[tree-ssa] Mainline merge plan

[Richard Earnshaw]

[...mudflap]
>  >
>  >If it's not critical anywhere, then I'm inclined to suggest that it should 
>  >be temporarily disabled everywhere for now, in the interests of sorting 
>  >out the main issue -- the merge of tree-ssa itself.  Once that is sorted 
>  >out we can go back to looking at mudflap.
> Or have it disabled by default and allow targets where it is supported
> to explicitly enable it.

that works for me.  I think you'd find that also allows you to close (or a 
least suspend) two tree-ssa PR's for now.

R.