Set the defaults properly for newly allocated submessages.

Also, pb_dec_submessage() should have used calloc() instead of malloc()
in the first place.

git-svn-id: https://svn.kapsi.fi/jpa/nanopb-dev@1083 e3a754e5-d11d-0410-8d38-ebb782a927b9

pb_decode.c

@@ -661,10 +661,11 @@ bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field
 #ifdef MALLOC_HEADER
         if (*(void**)dest == NULL)
         {
-            void *object = malloc(msg->size);
+            void *object = calloc(1, msg->size);
             if (!object)
                 return false;
             *(void**)dest = object;
+            pb_message_set_to_defaults(msg, object);
             dest = object;
         } else {
             dest = *(void**)dest;