dtrace: Add the 'oformat' libdtrace option

This option can be used to specify a format to use in DTrace output.
The following formats are supported:
- json
- xml
- html
- none (default DTrace output)

This is implemented using libxo and integrated into libdtrace. Client
code only works with the following API:

- dtrace_oformat_setup(dtrace_hdl_t *) -- to be called when output is starting.
- dtrace_oformat_teardown(dtrace_hdl_t *) -- to be called when output is finished
- dtrace_oformat(dtrace_hdl_t *) -- check if oformat is enabled.
- dtrace_set_outfp(FILE *) -- sets the output file for oformat.
- Ensure that oformat is correctly checked in the drop handler and record
processing callbacks.

This commit also adds tests which check if the generated output is
valid (JSON, XML) and extends the dtrace(1) describing the structured output.

Reviewed by: markj
Discussed with: phil
MFC after: 2 months
Sponsored by: Innovate UK
Differential Revision: https://reviews.freebsd.org/D41745

dtrace: avoid gcc9 Walloca-larger-than

gcc9 grew a new warning for unbounded allocas, such as the one in
dt_options_load. Remove both uses of alloca in dt_options.c.

Reviewed by: markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D22880

Fix an off-by-one in dt_opt_setenv().

The bug would cause incorrect behaviour when attempting to override
an already set environment variable with -x setenv, as long as the
variable is not the last one in the array.

Reported by: Samuel Lepetit <slepetit@apple.com>
MFC after: 2 weeks

Remove drti.o's dependency on libelf. This makes it possible to add DTrace
probes to userland programs and libraries without also needing to link
libelf.

dtrace -G places the __SUNW_dof symbol at the beginning of the DOF (DTrace
probe and provider metdata) section in the generated object file; drti.o
now just uses this symbol to locate the section. A complication occurs
when multiple dtrace-generated object files are linked together, since the
__SUNW_dof symbol defined in each file is global. This is handled by
using objcopy(1) to convert __SUNW_dof to a local symbol once drti.o has
been linked with the generated object file. Upstream, this is done using a
linker feature not present in GNU ld.

Differential Revision: https://reviews.freebsd.org/D1757
Reviewed by: rpaulo
MFC after: 1 month
Relnotes: yes

Mechanically convert cddl sun #ifdef's to illumos

Since the upstream for cddl code is now illumos not sun, mechanically
convert all sun #ifdef's to illumos #ifdef's which have been used in all
newer code for some time.

Also do a manual pass to correct the use if #ifdef comments as per style(9)
as well as few uses of #if defined(__FreeBSD__) vs #ifndef illumos.

MFC after: 1 month
Sponsored by: Multiplay

Revert r267898.

Bring the following change from the illumos-joyent repository:

commit 78e24ab6803bbe11ba37642624e1498ede5b239d
Author: Bryan Cantrill <bryan@joyent.com>
Date: Thu Oct 31 01:20:54 2013

OS-1688 DTrace count() with histogram
OS-2360 DTrace full width distribution histograms
OS-2361 DTrace frequency trails

MFC after: 2 weeks

1452 DTrace buffer autoscaling should be less violent

illumos/illumos-gate@6fb4854bed54ce82bd8610896b64ddebcd4af706

This fixes the tst.resize1.d and tst.resize2.d DTrace tests, which have
been failing since r261122 since they were causing dtrace(1) to attempt to
allocate and use large amounts of memory, and get killed by the OOM killer
as a result.

MFC after: 1 month

DTrace: Revert r249367

The following change from illumos brought caused DTrace to
pause in an interactive environment:

3026 libdtrace should set LD_NOLAZYLOAD=1 to help the pid provider

This was not detected during testing because it doesn't
affect scripts.

We shouldn't be changing the environment, especially since the
LD_NOLAZYLOAD option doesn't apply to our (GNU) ld.
Unfortunately the change from upstream was made in such a way
that it is very difficult to separate this change from the
others so, at least for now, it's better to just revert
everything.

Reference:
https://www.illumos.org/issues/3026

Reported by: Navdeep Parhar and Mark Johnston

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.

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

* Handle the different ioctl design.
* Make this file compile cleanly.