[mgcp] Move the network bits to a separate file...

This change separates the protocol from the actual network code
(bind, forward data). This will allow to more easily hook up the
RTP code from OpenBSC and to not use local sockets at all.
diff --git a/openbsc/src/Makefile.am b/openbsc/src/Makefile.am
index dec6359..a73399e 100644
--- a/openbsc/src/Makefile.am
+++ b/openbsc/src/Makefile.am
@@ -38,7 +38,7 @@
 
 isdnsync_SOURCES = isdnsync.c
 
-bsc_mgcp_SOURCES = mgcp/mgcp_main.c mgcp/mgcp_protocol.c mgcp/mgcp_vty.c \
+bsc_mgcp_SOURCES = mgcp/mgcp_main.c mgcp/mgcp_protocol.c mgcp/mgcp_network.c mgcp/mgcp_vty.c \
 		   msgb.c talloc.c debug.c select.c timer.c telnet_interface.c
 bsc_mgcp_LDADD = libvty.a