json_parse_ex: Remove redundant assignment to unused 'b'.

The static analyser complains 'Value stored to 'b' is never read'.

There isn't even much of a defence that it's just being defensive; we
ought to *know* it isn't used from that point on.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

json/json.c

@@ -676,7 +676,6 @@ json_value * json_parse_ex (json_settings * settings,
                               {
                                  if ( (++ state.ptr) == end)
                                  {
-                                    b = 0;
                                     break;
                                  }