Change LogReader API to be able to replace messages

The mutation API in LogReader was not able to express dropping messages,
or growing messages.  This enables more aggressive mutation.

Change-Id: I477482da4262483a780d15ebf8c98a51e37099f6
Signed-off-by: James Kuszmaul <james.kuszmaul@bluerivertech.com>
diff --git a/aos/flatbuffers.h b/aos/flatbuffers.h
index 607303c..e5de120 100644
--- a/aos/flatbuffers.h
+++ b/aos/flatbuffers.h
@@ -9,6 +9,7 @@
 #include "glog/logging.h"
 
 #include "aos/containers/resizeable_buffer.h"
+#include "aos/ipc_lib/data_alignment.h"
 #include "aos/macros.h"
 #include "aos/util/file.h"