GDB `cannotfix' pr state, require PR with xfail `moving forward'.

[Andrew Cagney]

> 
> - yank the existing xfail PR markings (but not the actual xfails) (they apply to old internal Red Hat and HP bug databases and hence are meaningless).

Just to clarify something here.  MichaelC wrote (on another thread):

 > ... you are talking
 > about 's/CLLbsNNNNN//', not 'g/CLLbsNNNNN/d'.
 >
 > I still think that's not useful in light of the progress we are
 > making but I would not be opposed to it happening.

`useful' doesn't come into this part of the equation.  Those references 
to an external bug database need to be removed.  The only thing up for 
negotiation on this one is the timing.

Andrew