osmo-bsc: gsm_timers_vty: Set global T_defs during vty_init

Otherwise any use of functions in gsm_timers_vty.c will fail because
g_vty_T_defs is never set (so it is NULL).

Change-Id: Ieeb27fdb06c965fa6b70aeb0f3b3f5169b1f2012

src/osmo-bsc/gsm_timers_vty.c

@@ -102,6 +102,7 @@ DEFUN(show_timer, show_timer_cmd,
 /* Install GSM timer configuration commands in the VTY. */
 void T_defs_vty_init(struct T_def *T_defs, int cfg_parent_node)
 {
+	g_vty_T_defs = T_defs;
 	install_element_ve(&show_timer_cmd);
 	install_element(cfg_parent_node, &cfg_timer_cmd);
 }