lost+found dir placement

[jb]

Hi,

Each fs should have its own lost+found directory.
It is used by fsck for placing recovered corrupted fs files in there.
This implies the dir must have already existed (it may not be mounted ad hoc
e.g. at boot time, during fs recovery).
 
In FreeBSD 9, I found lost+found dir under /mnt.
This is incorrect - /mnt is defined under all standards (Filesystem Hierarchy 
Standard, Unix directory structure) as "contains filesystem mount points".

So, lost+found dir should exist under root dir as /lost+found.

Any comments before I file a PR request ?
jb