nat: Fix compilation with nat not being enabled.

common_vty.c was including bsc_nat.h which tried to
get the sccp/sccp_types.h which is not required to be
installed. Move all structs using/embedding SCCP structures
into the bsc_nat_sccp.h and include. This should fix
the compilation.
diff --git a/openbsc/include/openbsc/bsc_nat_sccp.h b/openbsc/include/openbsc/bsc_nat_sccp.h
new file mode 100644
index 0000000..0a06a87
--- /dev/null
+++ b/openbsc/include/openbsc/bsc_nat_sccp.h
@@ -0,0 +1,92 @@
+/* NAT utilities using SCCP types */
+/*
+ * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2010 by On-Waves
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef BSC_NAT_SCCP_H
+#define BSC_NAT_SCCP_H
+
+#include <sys/types.h>
+#include <sccp/sccp_types.h>
+
+/*
+ * For the NAT we will need to analyze and later patch
+ * the received message. This would require us to parse
+ * the IPA and SCCP header twice. Instead of doing this
+ * we will have one analyze structure and have the patching
+ * and filter operate on the same structure.
+ */
+struct bsc_nat_parsed {
+	/* ip access prototype */
+	int ipa_proto;
+
+	/* source local reference */
+	struct sccp_source_reference *src_local_ref;
+
+	/* destination local reference */
+	struct sccp_source_reference *dest_local_ref;
+
+	/* called ssn number */
+	int called_ssn;
+
+	/* calling ssn number */
+	int calling_ssn;
+
+	/* sccp message type */
+	int sccp_type;
+
+	/* bssap type, e.g. 0 for BSS Management */
+	int bssap;
+
+	/* the gsm0808 message type */
+	int gsm_type;
+};
+
+/*
+ * Per SCCP source local reference patch table. It needs to
+ * be updated on new SCCP connections, connection confirm and reject,
+ * and on the loss of the BSC connection.
+ */
+struct sccp_connections {
+	struct llist_head list_entry;
+
+	struct bsc_connection *bsc;
+	struct bsc_msc_connection *msc_con;
+
+	struct sccp_source_reference real_ref;
+	struct sccp_source_reference patched_ref;
+	struct sccp_source_reference remote_ref;
+	int has_remote_ref;
+
+	/* status */
+	int con_type;
+	int con_local;
+
+	/* GSM audio handling. That is 32 * multiplex + ts */
+	int crcx;
+	int msc_timeslot;
+	int bsc_timeslot;
+
+	/* timeout handling */
+	struct timespec creation_time;
+};
+
+
+#endif