vl: Fix include style

vl: Fix include style

As explained in the thread starting at [0], the internal include style
should be »#include "path/to/header.h"« for non-system includes.

[0]
<http://news.gmane.org/find-root.php?message_id=%3c4E5802BE.6020206%40vmware.com%3e>

Signed-off-by: Kai Wasserbäch <kai@dev.carbon-project.org>
Signed-off-by: Brian Paul <brianp@vmware.com>