pcu_sock: add basic pcu interface support

Adds a basic version of a pcu socket interface, similar
to the one that can be found in osmo-bts.

Change-Id: Ib13cb4099d12fa71e9e0b8727e19ab29e11909b2
diff --git a/openbsc/include/openbsc/Makefile.am b/openbsc/include/openbsc/Makefile.am
index eb09e18..2740a5d 100644
--- a/openbsc/include/openbsc/Makefile.am
+++ b/openbsc/include/openbsc/Makefile.am
@@ -65,6 +65,8 @@
 	bsc_msc_data.h \
 	osmux.h \
 	paging.h \
+	pcu_if.h \
+	pcuif_proto.h \
 	rest_octets.h \
 	rrlp.h \
 	rs232.h \