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

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

Initiate deorbit burn for the i386-only a.out related support. Moves are
under way to move the remnants of the a.out toolchain to ports. As the
comment in src/Makefile said, this stuff is deprecated and one should not
expect this to remain beyond 4.0-REL. It has already lasted WAY beyond
that.

Notable exceptions:
gcc - I have not touched the a.out generation stuff there.
ldd/ldconfig - still have some code to interface with a.out rtld.
old as/ld/etc - I have not removed these yet, pending their move to ports.
some includes - necessary for ldd/ldconfig for now.

Tested on: i386 (extensively), alpha

Support a.out: avoid (%dx) in in/out instructions, and use an m4
macro to supply underscores for externals.

$Id$ -> $FreeBSD$

This commit was generated by cvs2svn to compensate for changes in r48907,
which included commits to RCS files with non-trunk default branches.

kgzldr is a kzipboot replacement for use with kgzip(8).

Development sponsored by Global Technology Associates, Inc.

Reviewed/tested by: abial