base-files: source functions.sh in /lib/functions/system.sh

The file /lib/functions/system.sh depends on find_mtd_index() and
find_mtd_part() located in /lib/function.sh, so let's source that
file.

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>

package/base-files/files/lib/functions/system.sh

@@ -1,5 +1,6 @@
 # Copyright (C) 2006-2013 OpenWrt.org
 
+. /lib/functions.sh
 . /usr/share/libubox/jshn.sh
 
 get_mac_binary() {