move libiu to osmo-iuh/libosmo-ranap

Remove libiu here, use the functions from libosmo-ranap instead, by applying
the ranap_ / RANAP_ prefix.

Corresponding change-id in osmo-iuh.git is I6a3f7ad15be03fb94689b4af6ccfa828c25f45c0

To be able to run the msc_vlr tests for RAN_UTRAN_IU without Iu client headers
available, add iu_dummy.h, containing mere function signatures that match
iu_dummy.c and a mostly empty struct ranap_ue_conn_ctx.

Make sure we can build with and without --enable-iu: include osmo-iuh headers
only with --enable-iu.

Change-Id: Ib8c4fcdb4766c5e575618b95ce16dce51063206b
diff --git a/src/gprs/sgsn_main.c b/src/gprs/sgsn_main.c
index d56af0e..25ee632 100644
--- a/src/gprs/sgsn_main.c
+++ b/src/gprs/sgsn_main.c
@@ -58,7 +58,6 @@
 #include <openbsc/sgsn.h>
 #include <openbsc/gprs_llc.h>
 #include <openbsc/gprs_gmm.h>
-#include <openbsc/iu.h>
 
 #include <osmocom/ctrl/control_if.h>
 #include <osmocom/ctrl/ports.h>
@@ -69,6 +68,10 @@
 
 #include "../../bscconfig.h"
 
+#if BUILD_IU
+#include <osmocom/ranap/iu_client.h>
+#endif
+
 #define _GNU_SOURCE
 #include <getopt.h>
 
@@ -322,7 +325,7 @@
 	.num_cat = ARRAY_SIZE(gprs_categories),
 };
 
-int sgsn_ranap_iu_event(struct ue_conn_ctx *ctx, enum iu_event_type type, void *data);
+int sgsn_ranap_iu_event(struct ue_conn_ctx *ctx, enum ranap_iu_event_type type, void *data);
 
 int main(int argc, char **argv)
 {
@@ -451,7 +454,7 @@
 		return 8;
 	}
 
-	iu_init(tall_bsc_ctx, sccp, gsm0408_gprs_rcvmsg_iu, sgsn_ranap_iu_event);
+	ranap_iu_init(tall_bsc_ctx, DRANAP, "OsmoSGSN-IuPS", sccp, gsm0408_gprs_rcvmsg_iu, sgsn_ranap_iu_event);
 #endif
 
 	if (daemonize) {