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

MFC r269077 (sbruno): libstand qdivrem warning fixes

libstand's qdivrem.c assumes that sizeof(int) == sizeof(long), this is not
true on amd64 I'm not quite positive this is the "correct" solution for
this but it does seem to compile and shut up the spew of warnings when
compiling libstand for userboot.

Add two _Static_asserts() so that in the future somebody will get a compile
failure if an architecture develops that violates the assumptions of this
code. (strongly suggested by jmg)

Change commetns to indicate int types instead of long. (noted by ian in
phabric review)

Phabric: https://phabric.freebsd.org/D443

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

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

Remove California Regent's clause 3, per letter

Add __divdi3() and __moddi3() to libstand. We will need them for UFS2.

Sponsored by: DARPA & NAI Labs.

Remove 'register' keyword.

Add __FBSDID()s to libstand

$Id$ -> $FreeBSD$

Move setjmp/longjmp implementations here from libc; no signal handling
in libstand, only for i386 until I locate an alpha setjmp/longjmp.

Minimal 64-bit gcc integer support for i386. This is kinda nasty, and
should be revisited once we decide whether the bootblocks need
quad arithmetic.