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

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

Reduce debugging output for netatalk routing events.

MFC after: 3 days

Cleanup of netatalk atalk layer includes, protocol definitions, and
routing:

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

- Make include guards consistent with our more general naming
convention.

- Rearrange and complete forward structure declarations in at_extern.h,
remove testing of guards of various other include files to protect
function declarations.

This leaves an ifdef _KERNEL in at_var.h, but from inspection it seems
likely that this file is not actually safe for inclusion in user space
still. However, since it's not included from within src/ so this does
not appear to be an issue (ifconfig, etc, have migrated to the generic
cross-protocol ioctls for address operations).

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

Imperfect synchronization solution to imperfect code: use a static 256
byte buffer in the stack for temporary printf results rather than a
global buffer without synchronization.

Compare pointers with NULL rather than 0, or treating them as boolans in
if statements.

at_rmx gets a $FreeBSD$ out of the deal also (this code appears to be
unused).

De-staticize and add prototype for main debug function. I'll turn
this into a DDB command in the next staticization run.

Staticize.

Fixed printf format errors.

Removed unused #includes.

Submitted by: archie@whistle.com

appletalk cleanups

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.