rs6000: Fix bootstrap

> On 18/01/2022 22:42, Segher Boessenkool wrote:
> > > +    default:
> > > +      break;
> > Please don't do that.  You can do
> >
> >    default:
> >      break;
> >      break;
> >      /* And just to make sure:  */
> >      break;
> >      break;
> >
> > and it will do exactly the same as not having a default at all.  Not
> > having such useless code is by far the most readable, so please don't
> > include a default case at all.
>
> I removed the default case. I hope this is what you wanted.

Unfortunately the removal of default: break; breaks bootstrap:
../../gcc/config/rs6000/rs6000.cc: In function ‘const char* rs6000_machine_from_flags()’:
../../gcc/config/rs6000/rs6000.cc:5940:10: error: enumeration value ‘PROCESSOR_PPC601’ not handled in switch [-Werror=switch]
 5940 |   switch (rs6000_cpu)
      |          ^
../../gcc/config/rs6000/rs6000.cc:5940:10: error: enumeration value ‘PROCESSOR_PPC603’ not handled in switch [-Werror=switch]
...
default: break; is needed to tell the -Wswitch warning that it is intentional
that not all enumerators are handled in the switch.

2022-01-19  Jakub Jelinek  <jakub@redhat.com>

	* config/rs6000/rs6000.cc (rs6000_machine_from_flags): Add default:.

gcc/config/rs6000/rs6000.cc

@@ -5958,6 +5958,9 @@ rs6000_machine_from_flags (void)
 
     case PROCESSOR_PPCE6500:
       return "e6500";
+
+    default:
+      break;
     }
 
   HOST_WIDE_INT flags = rs6000_isa_flags;