munin: dont autoconf if amavisd not installed

When running "munin-node-configure --shell" on a new box, the amavis
plug always gets enabled even though amavis is not installed.

I think the amavis plugin 'autoconf' stanza should perform more checks
than just whether /var/log/maillog and /usr/local/bin/logtail exist.

Perhaps like so?

(I easily get confused when working with diffs of diffs, so help is
welcome.)

Index: net/munin/patches/patch-plugins_node_d_amavis_in
===================================================================
RCS file: /cvs/ports/net/munin/patches/patch-plugins_node_d_amavis_in,v
diff -u -p -r1.4 patch-plugins_node_d_amavis_in
--- net/munin/patches/patch-plugins_node_d_amavis_in	11 Mar 2022 19:46:25 -0000	1.4
+++ net/munin/patches/patch-plugins_node_d_amavis_in	4 Aug 2026 22:17:48 -0000
@@ -26,7 +26,7 @@ Index: plugins/node.d/amavis.in
       group adm
  
  =head1 INTERPRETATION
-@@ -74,8 +74,8 @@ GPLv2
+@@ -74,14 +74,14 @@ GPLv2
  =cut
  
  
@@ -37,3 +37,8 @@ Index: plugins/node.d/amavis.in
  STATEFILE=$MUNIN_PLUGSTATE/amavis.offset
  
  if [ "$1" = "autoconf" ]; then
+-	if [ -f "${AMAVIS_LOG}" ] && [ -n "${LOGTAIL}" ] && [ -x "${LOGTAIL}" ] ; then
++	if [ -x /usr/local/sbin/amavisd ] && [ -f "${AMAVIS_LOG}" ] && [ -n "${LOGTAIL}" ] && [ -x "${LOGTAIL}" ] ; then
+ 		echo yes
+ 		exit 0
+ 	else