Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

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

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

Copy amd64 setjmp.h to x86 and replace amd64/i386/pc98 setjmp.h with stubs.

Remove 3rd clause, renumber, ok per email

Fix namespace issues by using visibility conditionals from
<sys/cdefs.h>.

style(9) <machine/setjmp.h> headers so they look mostly the same.

Work around a bug by adding struct tags. gcc-2.95 apparently gets the
check in the [basic.link] section of the C++ standard wrong. gcc-2.7.2.3
apparently doesn't do the check, so the bug doesn't affect RELENG_3.

PR: 16170, 21427
Submitted by: Max Khon <fjoe@lark.websci.ru> (i386 version)
Discussed with: jdp

sigset_t change (part 3 of 5)
-----------------------------

By introducing a new sigframe so that the signal handler operates
on the new siginfo_t and on ucontext_t instead of sigcontext, we
now need two version of sendsig and sigreturn.

A flag in struct proc determines whether the process expects an
old sigframe or a new sigframe. The signal trampoline handles
which sigreturn to call. It does this by testing for a magic
cookie in the frame.

The alpha uses osigreturn to implement longjmp. This means that
osigreturn is not only used for compatibility with existing
binaries. To handle the new sigset_t, setjmp saves it in
sc_reserved (see NOTE).

the struct sigframe has been moved from frame.h to sigframe.h
to handle the complex header dependencies that was caused by
the new sigframe.

NOTE: For the i386, the size of jmp_buf has been increased to hold
the new sigset_t. On the alpha this has been prevented by
using sc_reserved in sigcontext.

$Id$ -> $FreeBSD$

Suggested by: bde
Move sigjmp_buf and jmp_buf structure definitions to machine/setjmp.h
so that i386 can continue to use int as the basic register type and
alpha can use long. Bruce was concerned about possible differing
alignment. I've left the definition of _JBLEN in machine/setjmp.h
even though Bruce's example used the number directly. I don't know if
any other code relies on _JBLEN, so I left it to avoid potential
breakage.

Add a machine dependent header for the i386 jmp_buf size instead of piling
machine dependent definitions into src/include/setjmp.h.