r.d.n: add script to work around/implement a missing feature of debrebuild

Signed-off-by: Holger Levsen <holger@layer-acht.org>

bin/debrebuild_cache_limiter.sh

+#!/bin/bash
+#
+# Copyright 2025 Holger Levsen (holger@layer-acht.org)
+# released under the GPLv2
+
+CACHE=~rebuilderd/cache
+
+if [ ! -d $CACHE ] ; then
+	echo "$CACHE does not exist."
+	exit 1
+fi
+
+case $HOSTNAME in
+	ionos17*)	LIMIT=50  ;;
+	codethink*)	LIMIT=20  ;;
+	osuosl*)	LIMIT=333 ;;
+	infom07*)	LIMIT=200 ;; # FIXME: drop extra partition again?
+	infom08*)	LIMIT=100 ;;
+	riscv64*)	LIMIT=180 ;;
+	*)		echo "Limit for $HOSTNAME not defined."
+			exit 1 ;;
+esac
+
+# delete 1000 oldest files
+# FIXME: use atime, but then, this script should not exist in the first place... :)
+find $CACHE -type f -printf '%T+ %p\n' | sort | head -n 1000|cut -d ' ' -f2-|xargs sudo rm 
+
+set -e
+set -o pipefail	
+
+SIZE=$(du -sh $CACHE | grep G | cut -d 'G' -f 1)
+
+if [ $SIZE -gt $LIMIT ] ; then
+	echo "$CACHE is still ${SIZE}G, reducing further."
+	$0
+else
+	echo "$CACHE is ${SIZE}G, voila."
+fi
+
+exit 0