[PATCH v4] rust: support raw DPDK API

[Etelson, Gregory]

Hello Bruce,

> Hi Gregory, some high-level feedback:
>
> * I'd suggest for future revisions splitting this into two patches. The rust
> example should be separate from a patch adding the basic rust
> infrastructure.

In progress.

>
> * For the example, I'd suggest that the helloworld rust example should
> correspond to the regular "C" helloworld example, i.e just init DPDK and
> print helloworld. If we want a basic packet handling example, it should be
> an l2fwd one - again to align with the "C" examples.

The next patch update will not include that example.

>
> * However, in terms of the examples, if the idea is to provide higher level
> "rustic" APIs for DPDK, the examples should be written to use that. Any use
> of the low-level C APIs should be in a testing app only, rather than an example
> app. IMHO We want to encourage proper rust usage, not C-code just rewritten to
> use a different compiler.

This project, in its current stage, is a bit of an experiment.
I'm trying to figure out how much effort it will take to provide DPDK API for 
Rust application.
Rust API is the final goal.

Regards,
Gregory