newfs_hammer hammer_fsbuf_head_t build failure.

[Kyle Butt <kylebutt@xxxxxxxxx>]

with the most recent head, buildworld fails on newfs_hammer. At first it was
complaining about hammer_alist_t, but I found that and included "hammer_alist.h"

It's now complaining about hammer_fsbuf_head_t, which I can't find anywhere.
I'm updating via rsync from theshell.com if that helps someone find a stale
entry somewhere.

Kyle.