Add buffer tracing to the dispatch tracer

Change-Id: I56f25d653b71a25c70e6c5c1a93dd9c5158f2079
Signed-off-by: Dave Barach <dave@barachs.net>
diff --git a/src/vlib/trace.c b/src/vlib/trace.c
index e3b2898..7062113 100644
--- a/src/vlib/trace.c
+++ b/src/vlib/trace.c
@@ -131,7 +131,7 @@
   /* *INDENT-ON* */
 }
 
-static u8 *
+u8 *
 format_vlib_trace (u8 * s, va_list * va)
 {
   vlib_main_t *vm = va_arg (*va, vlib_main_t *);