lib: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

Remove $FreeBSD$: two-line .h pattern

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

Resolve conflicts between macros in fenv.h and ieeefp.h

This is a follow-up to r321483, which disabled -Wmacro-redefined for
some lib/msun tests.

If an application included both fenv.h and ieeefp.h, several macros such
as __fldcw(), __fldenv() were defined in both headers, with slightly
different arguments, leading to conflicts.

Fix this by putting all the common macros in the machine-specific
versions of ieeefp.h. Where needed, update the arguments in places
where the macros are invoked.

This also slightly reduces the differences between the amd64 and i386
versions of ieeefp.h.

Reviewed by: kib
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D15633

lib: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Bugfix: feenableexcept() and fedisableexcept() should just return the
old exception mask, not mask | ~FE_ALL_EXCEPT.

MFC after: 2 weeks

Use #include "fenv.h" instead of #include <fenv.h>. This makes it
more convenient to compile the math library by itself.

Requested by: bde

Replace two lines accidentally removed in r226218. Thanks to bde
for noticing this.

Provide external definitions of all of the standardized functions in
fenv.h that are currently inlined.

The definitions are provided in fenv.c via 'extern inline'
declaractions. This assumes the compiler handles 'extern inline' as
specified in C99, which has been true under FreeBSD since 8.0.

The goal is to eventually remove the 'static' keyword from the inline
definitions in fenv.h, so that non-inlined references all wind up
pointing to the same external definition like they're supposed to.
I am deferring the second step to provide a window where
newly-compiled apps will still link against old math libraries.
(This isn't supported, but there's no need to cause undue breakage.)

Reviewed by: stefanf, bde

A new jail(8) with a configuration file, to replace the work currently done
by /etc/rc.d/jail.

Create the altix project branch. The altix project will add support
for the SGI Altix 350 to FreeBSD/ia64. The hardware used for porting
is a two-module system, consisting of a base compute module and a
CPU expansion module. SGI's NUMAFlex architecture can be an excellent
platform to test CPU affinity and NUMA-aware features in FreeBSD.

MFC r203441:
Placate new binutils, by using 16-bit %ax instead of 32-bit %eax as an
argument for fnstsw. Explicitely specify sizes for the XMM control and
status word and X87 control and status words.

Placate new binutils, by using 16-bit %ax instead of 32-bit %eax as an
argument for fnstsw. Explicitely specify sizes for the XMM control and
status word and X87 control and status words.

Reviewed by: das
Tested by: avg
MFC after: 2 weeks

- Import the HEAD csup code which is the basis for the cvsmode work.

Remove an unneeded fnstcw instruction.

Noticed by: bde

Make the fenv.h routines work for programs that use SSE for
floating-point arithmetic on i386. Now I'm going to make excuses
for why this code is kinda scary:

- To avoid breaking the ABI with 5.3-RELEASE, we can't change
sizeof(fenv_t). I stuck the saved mxcsr in some discontiguous
reserved bits in the existing structure.

- Attempting to access the mxcsr on older processors results
in an illegal instruction exception, so support for SSE must
be detected at runtime. (The extra baggage is optimized away
if either the application or libm is compiled with -msse{,2}.)

I didn't run tests to ensure that this doesn't SIGILL on older 486's
lacking the cpuid instruction or on other processors lacking SSE.
Results from running the fenv regression test on these processors
would be appreciated. (You'll need to compile the test with
-DNO_STRICT_DFL_ENV.) If you have an 80386, or if your processor
supports SSE but the kernel didn't enable it, then you're probably out
of luck.

Also, I un-inlined some of the functions that grew larger as a result
of this change, moving them from fenv.h to fenv.c.

Add an fenv.h implementation for the i386 port.

Reviewed by: standards@