vcl: add apis that expos fifo as buffer

Change-Id: I4bd9c9f73499711e04b38d53daa5c917a4285bf5
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vcl/vcl_private.h b/src/vcl/vcl_private.h
index 11d957a..5f3c1ec 100644
--- a/src/vcl/vcl_private.h
+++ b/src/vcl/vcl_private.h
@@ -139,6 +139,7 @@
 
 typedef struct
 {
+  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
 #define _(type, name) type name;
   foreach_app_session_field
 #undef _