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

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

Adjust the system endian and a.out headers to be more MI and cross-building
friendly. Use the systems headers rather than local versions.

Reviewed by: ru

Fix the type of the NULL arg to execl()

Idea from: Theo de Raadt <deraadt@openbsd.org>

Add support for creating a.out output files in addition to ELF.
This allows booting from compressed binaries using older bootstraps.

Thanks to: dwmalone

$Id$ -> $FreeBSD$

This commit was generated by cvs2svn to compensate for changes in r48905,
which included commits to RCS files with non-trunk default branches.

kgzip is a kzip(8) replacement able to compress and link bootable
32-bit binaries in both ELF and a.out format.

Development sponsored by Global Technology Associates, Inc.

Reviewed/tested by: abial