Add SGs Interface

Add an SGs interface (3GPP TS 29.118) to osmo-msc in order to support
SMS tunneling and Circuit Switched Fallback (CSFB)

Change-Id: I73359925fc1ca72b33a1466e6ac41307f2f0b11d
Related: OS#3615
diff --git a/tests/msc_vlr/Makefile.am b/tests/msc_vlr/Makefile.am
index 8a5e719..dea63e5 100644
--- a/tests/msc_vlr/Makefile.am
+++ b/tests/msc_vlr/Makefile.am
@@ -57,6 +57,7 @@
 
 noinst_HEADERS = \
 	msc_vlr_tests.h \
+	stubs.h \
 	$(NULL)
 
 EXTRA_DIST = \