Use thread local storage for thread index

This patch deprecates stack-based thread identification,
Also removes requirement that thread stacks are adjacent.

Finally, possibly annoying for some folks, it renames
all occurences of cpu_index and cpu_number with thread
index. Using word "cpu" is misleading here as thread can
be migrated ti different CPU, and also it is not related
to linux cpu index.

Change-Id: I68cdaf661e701d2336fc953dcb9978d10a70f7c1
Signed-off-by: Damjan Marion <damarion@cisco.com>

src/vnet/lldp/lldp_input.c

@@ -35,7 +35,7 @@ typedef struct
 static void
 lldp_rpc_update_peer_cb (const lldp_intf_update_t * a)
 {
-  ASSERT (os_get_cpu_number () == 0);
+  ASSERT (vlib_get_thread_index () == 0);
 
   lldp_intf_t *n = lldp_get_intf (&lldp_main, a->hw_if_index);
   if (!n)