Add Osmux IPv6 support

A new osmux bind-ip-v6 VTY command is added, similar to what's already
available for RTP. This way the user can decide whether to support IPv4,
IPv6 or both types of IP versions.

Both IP sockets are by default disabled, and must be explicitly enabled
by setting the bind-ip in the VTY configuration.

Change-Id: I446cd7da217e9f4a74995d7784ae55dcc60a29b7
diff --git a/include/osmocom/mgcp/mgcp.h b/include/osmocom/mgcp/mgcp.h
index 4c541cb..2005e4f 100644
--- a/include/osmocom/mgcp/mgcp.h
+++ b/include/osmocom/mgcp/mgcp.h
@@ -160,7 +160,8 @@
 	/* Osmux usage policy: */
 	enum osmux_usage osmux_use;
 	/* addr to bind the server to */
-	char osmux_addr[INET6_ADDRSTRLEN];
+	char *osmux_addr_v4;
+	char *osmux_addr_v6;
 	/* The BSC-NAT may ask for enabling osmux on demand. This tells us if
 	 * the osmux socket is already initialized.
 	 */