Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Clean up DDP layer netatalk code:

- General style(9) cleanup -- white space, braces, line wraps, etc.

- Annotate a lack of synchronization the global route cache if the input
routine is invoked with parallelism.

- Remove unused debugging code.

/* -> /*- for license, minor formatting changes, insert COPYRIGHT into files

Procotol control block locking for netatalk DDP.

Rename 'ddpcb' variable to 'ddpcb_list' to better distinguish it from
'struct ddpcb'.

Make ddp_ports static, as it's not used outside of ddp_usrreq.c.

Inspired by: Day spent hiking to hot springs in Taiwan
Powered by: Asia BSDCon 2004

Change #ifdef KERNEL to #ifdef _KERNEL in the public headers. "KERNEL"
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot). This is consistant with the other
BSD's who made this change quite some time ago. More commits to come.

Moved misplaced extern declarations.

Fixed another sloppy common-style declaration (staticized it).

Obtained from: netatalk distribution netatalk@itd.umich.edu

Kernel Appletalk protocol support
both CAP and netatalk can make use of this..
still needs some owrk but it seemd the right tiime to commit it
so other can experiment.