bsc: Add code responsible for connecting, reconnecting to the MSC

Add the code that is forwarding data, from and to the MSC, also
handling ping/pong timers and authentication. Hook it into the
osmo_bsc. The code is only compile tested and ported from the
on-waves/bsc-master branch.
diff --git a/openbsc/src/bsc/Makefile.am b/openbsc/src/bsc/Makefile.am
index db497be..dc1e701 100644
--- a/openbsc/src/bsc/Makefile.am
+++ b/openbsc/src/bsc/Makefile.am
@@ -6,7 +6,7 @@
 
 
 osmo_bsc_SOURCES = osmo_bsc_main.c osmo_bsc_rf.c osmo_bsc_vty.c osmo_bsc_api.c \
-		   osmo_bsc_grace.c \
+		   osmo_bsc_grace.c osmo_bsc_msc.c \
 		   $(top_srcdir)/src/debug.c $(top_srcdir)/src/bsc_msc.c \
 		   $(top_srcdir)/src/bsc_init.c
 osmo_bsc_LDADD = $(top_builddir)/src/libvty.a \