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/tests/msc_vlr/Makefile.am b/tests/msc_vlr/Makefile.am
index 6d51d6e..3ae0c84 100644
--- a/tests/msc_vlr/Makefile.am
+++ b/tests/msc_vlr/Makefile.am
@@ -50,13 +50,6 @@
 	$(top_builddir)/src/libtrau/libtrau.a \
 	$(top_builddir)/src/libmgcp/libmgcp.a \
 	$(top_builddir)/src/libcommon/libcommon.a \
-	$(NULL)
-if BUILD_IU
-COMMON_LDADD += \
-	$(top_builddir)/src/libiu/libiu.a \
-	$(NULL)
-endif
-COMMON_LDADD += \
 	$(LIBSMPP34_LIBS) \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOGSM_LIBS) \
@@ -76,10 +69,10 @@
 	-Wl,--wrap=a_iface_tx_dtap \
 	-Wl,--wrap=a_iface_tx_clear_cmd \
 	-Wl,--wrap=a_iface_tx_paging \
-	-Wl,--wrap=iu_tx \
-	-Wl,--wrap=iu_tx_release \
-	-Wl,--wrap=iu_tx_common_id \
-	-Wl,--wrap=iu_page_cs \
+	-Wl,--wrap=ranap_iu_tx \
+	-Wl,--wrap=ranap_iu_tx_release \
+	-Wl,--wrap=ranap_iu_tx_common_id \
+	-Wl,--wrap=ranap_iu_page_cs \
 	-Wl,--wrap=msc_stop_paging \
 	-Wl,--wrap=gsm340_gen_scts \
 	-Wl,--wrap=RAND_bytes \