Fix to inex#829

Previously the counters were not reset in case the API was unreachable.
After writing data to RRDs new counters need to be initialized.

tools/runtime/sflow/sflow-to-rrd-handler

@@ -210,7 +210,6 @@ while (<SFLOWTOOL>) {
  my $newmactable = reload_mactable($client, $macdbrest);
  if ($newmactable) {
  $mactable = $newmactable;
- $matrix = matrix_init($mactable, $infraid);
  $mactablereloadfails = 0;
  } else {
  $mactablereloadfails++;
@@ -221,6 +220,7 @@ while (<SFLOWTOOL>) {
  die "FATAL: could not reload mactable after $mactabletimeout seconds. Aborting.\n";
  }
  }
+ $matrix = matrix_init($mactable, $infraid);
  $debug && print STDERR "DEBUG: flush completed at ".time()."\n";
  }
 }