msgpack: make msgpackffi use encode_max_depth option

Msgpack Lua module is not a simple set of functions. It is a
global serializer object used by plenty of other Lua and C
modules. Msgpack as a serializer can be configured, and in theory
its configuration updates should affect all other modules. For
example, a user could change encode_max_depth:

    require('msgpack').cfg({encode_max_depth = <new_value>})

And that would make tuple:update() accept tables with <new_value>
depth without a crop.

But in fact msgpack configuration didn't affect some places, such
as this one. And all the others who use msgpackffi.

This patch fixes it, for encode_max_depth option. Other options
are still ignored.

Part of #4434

(cherry picked from commit 4bb253f7)