V.42bis: integration and unit test

 - Edit previously committed V.42bis implementation to function
   outside IAXmodem.
 - Add unit test to verify the correct function of V.42bis

Change-Id: I689413f2541b6def0625ce6bd96f1f488f05f99d
diff --git a/openbsc/tests/sgsn/Makefile.am b/openbsc/tests/sgsn/Makefile.am
index 1447577..9250632 100644
--- a/openbsc/tests/sgsn/Makefile.am
+++ b/openbsc/tests/sgsn/Makefile.am
@@ -61,6 +61,7 @@
         $(top_builddir)/src/gprs/slhc.o \
         $(top_builddir)/src/gprs/gprs_sndcp_comp.o \
         $(top_builddir)/src/gprs/gprs_sndcp_pcomp.o \
+        $(top_builddir)/src/gprs/v42bis.o \
 	$(top_builddir)/src/libcommon/libcommon.a \
 	$(LIBOSMOABIS_LIBS) \
 	$(LIBOSMOCORE_LIBS) \