*: fix fallout from -Wunused-parameter

function                                             old     new   delta
bbunpack                                             358     366      +8
passwd_main                                         1070    1072      +2
handle_incoming_and_exit                            2651    2653      +2
getpty                                                88      86      -2
script_main                                          975     972      -3
inetd_main                                          2036    2033      -3
dname_enc                                            377     373      -4
make_new_session                                     474     462     -12
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/5 up/down: 12/-24)            Total: -12 bytes
   text    data     bss     dec     hex filename
 797429     658    7428  805515   c4a8b busybox_old
 797417     658    7428  805503   c4a7f busybox_unstripped

diff --git a/networking/Kbuild b/networking/Kbuild
index e06a124..44258e9 100644
--- a/networking/Kbuild
+++ b/networking/Kbuild
@@ -17,7 +17,7 @@
 lib-$(CONFIG_HOSTNAME)     += hostname.o
 lib-$(CONFIG_HTTPD)        += httpd.o
 lib-$(CONFIG_IFCONFIG)     += ifconfig.o interface.o
-lib-$(CONFIG_IFENSLAVE)    += ifenslave.o
+lib-$(CONFIG_IFENSLAVE)    += ifenslave.o interface.o
 lib-$(CONFIG_IFUPDOWN)     += ifupdown.o
 lib-$(CONFIG_INETD)        += inetd.o
 lib-$(CONFIG_IP)           += ip.o