use sudo for unbound statistics

Debian 12 by default uses an unix domain socket for access to
the control interface of unbound.  To make it more secure and
allow the RRD user only to call "unbound-control stats" and
nothing else, a small sudo wrapper is now needed.

`/usr/local/sbin/unbound-stats` should contain:

```shell
/usr/sbin/unbound-control stats
```

and the user running the unbound.pl rrd script must be permitted
to run `sudo /usr/local/sbin/unbound-stats`.

runall.sh

@@ -28,7 +28,7 @@ SCRIPTPATH=.
 #
 # set sleep time in seconds between calls
 # total script runtime should not exceed 5 minutes!
-RRD_WAIT=${RRD_WAIT:-16}
+RRD_WAIT=${RRD_WAIT:-2}
 
 #
 # how many graphs should be rendered?

unbound.pl

@@ -75,7 +75,7 @@
 }
 
 # get data
-open STATUS, '/usr/sbin/unbound-control stats|' or die "can't open unbound-control: $!";
+open STATUS, 'sudo /usr/local/sbin/unbound-stats|' or die "can't open unbound-stats: $!";
 my %stats = (
     'total.num.cachehits' => 0,
     'total.num.cachemiss' => 0,
@@ -87,7 +87,7 @@
     my ($key, $value) = split /=/, $line, 2;
     $stats{$key} = $value;
 }
-close STATUS or die "can't close unbound-control: $!";
+close STATUS or die "can't close unbound-stats: $!";
 
 # update database
 RRDs::update($datafile,