Add basic SI2quater support

* support for sending arbitrary static SI2quater.
* vty interface for neightbor EARFCNs specific to SI2quater.
* dynamic generation of SI2quater messages.
* unit test for SI2quater messages.

Fixes: OS#1630
diff --git a/openbsc/tests/gsm0408/Makefile.am b/openbsc/tests/gsm0408/Makefile.am
index 1c29ece..ee04102 100644
--- a/openbsc/tests/gsm0408/Makefile.am
+++ b/openbsc/tests/gsm0408/Makefile.am
@@ -7,6 +7,7 @@
 gsm0408_test_SOURCES = gsm0408_test.c
 gsm0408_test_LDADD =	$(top_builddir)/src/libbsc/libbsc.a \
 			$(top_builddir)/src/libmsc/libmsc.a \
+			$(top_builddir)/src/libtrau/libtrau.a \
 			$(top_builddir)/src/libbsc/libbsc.a \
 			$(top_builddir)/src/libcommon/libcommon.a \
-			$(LIBOSMOCORE_LIBS) $(LIBOSMOGSM_LIBS) -ldbi
+			$(LIBOSMOCORE_LIBS) $(LIBOSMOGSM_LIBS) $(LIBOSMOABIS_LIBS) -ldbi