Move udhcp to new NOMMU helpers.
Fix server part to compile under NOMMU.
Client is not compilable yet.
On MMU everything compiles (and maybe even works :)
diff --git a/networking/udhcp/Kbuild b/networking/udhcp/Kbuild
index 57d2511..aed40b9 100644
--- a/networking/udhcp/Kbuild
+++ b/networking/udhcp/Kbuild
@@ -6,9 +6,9 @@
 #
 
 lib-y:=
-lib-$(CONFIG_APP_UDHCPC)        += common.o options.o packet.o pidfile.o \
+lib-$(CONFIG_APP_UDHCPC)        += common.o options.o packet.o \
                                    signalpipe.o socket.o
-lib-$(CONFIG_APP_UDHCPD)        += common.o options.o packet.o pidfile.o \
+lib-$(CONFIG_APP_UDHCPD)        += common.o options.o packet.o \
                                    signalpipe.o socket.o
 lib-$(CONFIG_APP_UDHCPC)        += dhcpc.o clientpacket.o clientsocket.o \
                                    script.o