Fix various compiler warnings in hnb-gw code

Since we finally started to use -Wall, the related warnings became
visible.

Change-Id: I516700eab2aa7c3412dd62775c4960aed9d4b682
diff --git a/src/iu_client.c b/src/iu_client.c
index 17d955d..3ee900c 100644
--- a/src/iu_client.c
+++ b/src/iu_client.c
@@ -25,12 +25,16 @@
 #include <string.h>
 #include <stdbool.h>
 
+#include <asn1c/asn1helpers.h>
+
 #include <osmocom/ranap/iu_client.h>
 
 #include <osmocom/core/logging.h>
 #include <osmocom/crypt/auth.h>
 #include <osmocom/gprs/gprs_msgb.h>
 #include <osmocom/sigtran/sccp_sap.h>
+#include <osmocom/sigtran/sccp_helpers.h>
+#include <osmocom/ranap/ranap_common_cn.h>
 #include <osmocom/ranap/ranap_ies_defs.h>
 #include <osmocom/ranap/ranap_msg_factory.h>