Register GSM_BTS_TYPE_UNKNOWN in bsc_hack.c

The way the VTY configuration sytem works is that it first registers a
BTS of type GSM_BTS_TYPE_UNKNOWN and then sets the type correctly (after
encountering the type statement). This makes sure that registering a BTS
of type UNKNOWN succeeds.
diff --git a/openbsc/src/bts_unknown.c b/openbsc/src/bts_unknown.c
new file mode 100644
index 0000000..1e604a9
--- /dev/null
+++ b/openbsc/src/bts_unknown.c
@@ -0,0 +1,40 @@
+/* Generic BTS - VTY code tries to allocate this BTS before type is known */
+
+/* (C) 2010 by Daniel Willmann <daniel@totalueberwachung.de>
+ *
+ * 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.
+ *
+ */
+
+#include <sys/types.h>
+
+#include <openbsc/gsm_data.h>
+#include <openbsc/tlv.h>
+#include <openbsc/abis_nm.h>
+
+static struct gsm_bts_model model_unknown = {
+	.type = GSM_BTS_TYPE_UNKNOWN,
+	.nm_att_tlvdef = {
+		.def = {
+		},
+	},
+};
+
+int bts_model_unknown_init(void)
+{
+	return gsm_bts_model_register(&model_unknown);
+}