libgb: remove dependencies to openbsc/vty.h and openbsc/gsm_data.h

Rather than using openbsc internal data/functions, we now use only
internal and libosmocore-provided ones.
diff --git a/openbsc/src/libgb/common_vty.c b/openbsc/src/libgb/common_vty.c
new file mode 100644
index 0000000..269df8c
--- /dev/null
+++ b/openbsc/src/libgb/common_vty.c
@@ -0,0 +1,63 @@
+/* OpenBSC VTY common helpers */
+/* (C) 2009-2012 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2009-2010 by Holger Hans Peter Freyther
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <osmocom/core/talloc.h>
+
+#include <osmocom/vty/telnet_interface.h>
+#include <osmocom/vty/command.h>
+#include <osmocom/vty/buffer.h>
+#include <osmocom/vty/vty.h>
+
+/* Down vty node level. */
+gDEFUN(libgb_exit,
+       libgb_exit_cmd, "exit", "Exit current mode and down to previous mode\n")
+{
+	switch (vty->node) {
+	case L_NS_NODE:
+	case L_BSSGP_NODE:
+		vty->node = CONFIG_NODE;
+		vty->index = NULL;
+		break;
+	default:
+		break;
+	}
+	return CMD_SUCCESS;
+}
+
+/* End of configuration. */
+gDEFUN(libgb_end,
+       libgb_end_cmd, "end", "End current mode and change to enable mode.")
+{
+	switch (vty->node) {
+	case L_NS_NODE:
+	case L_BSSGP_NODE:
+		vty_config_unlock(vty);
+		vty->node = ENABLE_NODE;
+		vty->index = NULL;
+		vty->index_sub = NULL;
+		break;
+	default:
+		break;
+	}
+	return CMD_SUCCESS;
+}