*: add INSERTs to *.src files where appropriate

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/udhcp/Config.src b/networking/udhcp/Config.src
index f5840a9..aac8856 100644
--- a/networking/udhcp/Config.src
+++ b/networking/udhcp/Config.src
@@ -3,6 +3,8 @@
 # see scripts/kbuild/config-language.txt.
 #
 
+INSERT
+
 config UDHCPD
 	bool "udhcp server (udhcpd)"
 	default y