Netlink parser v5 bis

[Fabien Siron]

Hello again,

This second series for version 5 of netlink parser corrects the issue
with tab that happens in the previous message, I am sorry.

Changes since v4:
* Change iov_decoder to iov_decode and IOV_DECODER_* to IOV_DECODE_*.
* Squash commit old commit 5 and old commit 6 to current commit 4.
* Some minor fixes.

Regards,
--
Fabien Siron