Use PC-relative relocations for USDT probe sites on i386 and amd64.

When recording probe site addresses in the output DOF file, dtrace -G
needs to emit relocations for the .SUNW_dof section in order to obtain
the addresses of functions containing probe sites. DTrace expects the
addresses to be relative to the base address of the final ELF file,
and the amd64 USDT implementation was relying on some unspecified and
incorrect behaviour in the base system GNU ld to achieve this.

This change reimplements the probe site relocation handling to allow
USDT to be used with lld and newer GNU binutils. Specifically, it
makes use of R_X86_64_PC64/R_386_PC32 relocations to obtain the
probe site address relative to the DOF file address, and adds and uses a
new DOF relocation type which computes the final probe site address using
these relative offsets.

Reported by and discussed with: Rafael Espíndola
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D9374

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

DTrace imposes a 128-byte limit on the length of the function component of
a probe name. When dtrace -G builds up a DOF section for the specified
provider(s), the probe function names are truncated to fit in this limit.
The DOF is later used to build the symbol table for the generated object
file, so the table can end up with truncated references, causing link
errors.

Instead of potentially truncating symbol table entries, write the full
function name to the DOF string table and allow the kernel to enforce the
128-byte function name limit when a process attempts to load its DOF.

PR: 194757
Differential Revision: https://reviews.freebsd.org/D1175
Reviewed by: rpaulo
MFC after: 2 weeks

MFV r258379;

4248 dtrace(1M) should never create DOF with empty probes section
4249 Only probes from the first DTrace object file will be included

Illumos Revision: 4a20ab41aadcb81c53e72fc65886e964e9add59

Reference:
https://www.illumos.org/issues/4248
https://www.illumos.org/issues/4249

Obtained from: Illumos
MFC after: 1 month

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.

Leave out some header files.