add libiu

Co-Authored by dwillmann, laforge, nhofmeyr

Change-Id: Iffc26f9c73cb15463948f7435b72ac1747aabdb3
diff --git a/openbsc/configure.ac b/openbsc/configure.ac
index fbf2930..f63d61f 100644
--- a/openbsc/configure.ac
+++ b/openbsc/configure.ac
@@ -203,6 +203,7 @@
     src/libmgcp/Makefile
     src/libcommon/Makefile
     src/libfilter/Makefile
+    src/libiu/Makefile
     src/osmo-nitb/Makefile
     src/osmo-bsc/Makefile
     src/osmo-bsc_nat/Makefile