fix bird format; forget ','

Signed-off-by: Marek Küthe <m.k@mk16.de>

build_maxlen_filter.sh

@@ -5,6 +5,8 @@ if ! jq --version &> /dev/null; then
     exit 1
 fi
 
+filter=
+
 for file in *.json; do
     [[ $file =~ ^(schema.json)$ ]] && continue
     for prefix in $(jq -r ".route | keys[]" "$file"); do
@@ -13,6 +15,10 @@ for file in *.json; do
         if [ "$maxlen" == "null" ]; then
             maxlen=64
         fi
-        echo "$prefix{$prefixlen,$maxlen}"
+        filter="$filter$prefix{$prefixlen,$maxlen},\n"
     done
 done
+
+filter=${filter::-3}
+
+echo -e $filter