Implement -Wimplicit-fallthrough (take 2): fix missing breaks

[Richard Biener]

On Fri, 29 Jul 2016, Marek Polacek wrote:

> On Fri, Jul 29, 2016 at 01:46:11AM -0500, Segher Boessenkool wrote:
> > On Thu, Jul 28, 2016 at 05:57:34PM +0200, Marek Polacek wrote:
> > > Segher, is the rs6000.c part ok?
> > 
> > Yes, that looks fine, thanks!  Will you handle the backports as well?
> 
> Happy to, just not sure about 4.9.  Richi, is it ok to commit a patch
> adding break; into 4.9?

Yes.

Thanks,
Richard.