Add `netif' to the BEFORE line -- not sure why this was not here before.

We need it to make sure that we make writeable mounts for /var, which
the emulab version of netif writes into.

tmcd/freebsd5/cdboot/cdroot

 # PROVIDE: cdroot
-# BEFORE: disks
+# BEFORE: disks netif
 # KEYWORD: FreeBSD
 
 #