messaging3: Push down the self-send callback

messaging3: Push down the self-send callback

In the messaging_read receivers we already defer the callback: We need to
reply on potentially different tevent contexts, thus the defer_callback.

The callback case in messaging_dispatch_rec was direct before this
patch. This changes messaging_dispatch_rec to also defer the callback
in the self-send case.

Now we need only two roundtrips in local-messaging-read1 :-)

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>