Cleanup the package cache after install or upgrade

rootfs/etc/pacman.conf

 [options]
-CacheDir = /tmp/pacman/pkg
 Architecture = auto
 SigLevel = Required DatabaseOptional
 LocalFileSigLevel = Optional

rootfs/usr/share/libalpm/hooks/package-cleanup.hook

+[Trigger]
+Operation = Install
+Operation = Upgrade
+Type = Package
+Target = *
+
+[Action]
+Description = Cleaning up package cache...
+Depends = coreutils
+When = PostTransaction
+Exec = /usr/bin/rm -rf /var/cache/pacman/pkg /var/lib/pacman/sync