Warn but dont fail the build on STABS debuginfo (RhBug:725378, others)

- debugedit doesn't support STABS but there are some crazy cases
  like PPC Linux kernel which contains both STABS and DWARF debuginfo
  sections, manually added. A better fix would be erroring out
  if we didn't find any usable debuginfo and warning otherwise but
  this at least folks get their kernels built.

tools/debugedit.c

@@ -1588,7 +1588,7 @@ main (int argc, char *argv[])
 	  if (strcmp (name, ".stab") == 0)
 	    {
 	      fprintf (stderr, "Stabs debuginfo not supported: %s\n", file);
-	      exit (1);
+	      break;
 	    }
 	  if (strcmp (name, ".debug_info") == 0)
 	    edit_dwarf2 (dso);