From: Joe Perches <joe@perches.com>
Date: Thu, 12 May 2011 13:36:10 -0700

> Save a memset, initialize only the portion necessary.
> 
> packet_snd either gets this structure completely from
> memcpy_fromiovec or uses only the hdr_len set to 0,
> so don't always initialize the structure to 0.
> 
> Signed-off-by: Joe Perches <joe@perches.com>

On ARM this won't be tightly packed, therefore you'll leave
uninitialized pieces of padding in this structure and this
thing is an "on-the-wire" network header.

I'm not applying this.