VSM data are aligned to 32/64 bit boundary

Till now the VSM buffer was aligned to 16 bit boundary
which could possibly cause problems on RISC architectures
when accessing the message data in unsafe manner.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

src/msg.cpp

@@ -19,6 +19,7 @@
 */
 
 #include "msg.hpp"
+#include "../include/zmq.h"
 
 #include <string.h>
 #include <errno.h>
@@ -29,6 +30,11 @@
 #include "likely.hpp"
 #include "err.hpp"
 
+//  Check whether the sizes of public representation of the message (zmq_msg_t)
+//  and private represenation of the message (zmq::msg_t) match.
+typedef char zmq_msg_size_check
+    [2 * ((sizeof (zmq::msg_t) == sizeof (zmq_msg_t)) != 0) - 1];
+
 bool zmq::msg_t::check ()
 {
      return u.base.type >= type_min && u.base.type <= type_max;