Add counter for the number of barrier syncs performed.

Change-Id: I42b26c8f95c17577006f13e3419b8ccc9ef7c4f3
Signed-off-by: Todd Foggoa <tfoggoa@cisco.com>
diff --git a/vlib/vlib/threads.h b/vlib/vlib/threads.h
index 6c16878..5773ed0 100644
--- a/vlib/vlib/threads.h
+++ b/vlib/vlib/threads.h
@@ -93,6 +93,7 @@
   u32 instance_id;
   vlib_thread_registration_t *registration;
   u8 *name;
+  u64 barrier_sync_count;
 
   long lwp;
   int dpdk_lcore_id;