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 $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\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spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD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

librtld_db: Handle shlibs with discontiguous mappings.

Some shared libraries specify mappings that leave a gap (actually a
MAP_GUARD mapping) in between the file mappings (libcrypto.so was
the one I found), and this would cause rd_loadobj_iter() to report
the mapping info incorrectly, leaving out rdl_path and misreporting
rdl_offset for file mappings after the gap. Fix rd_loadobj_iter()
to handle this situation.

Reviewed by: markj
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D32950

librtld_db: Handle anonymous mappings below the first file mapping.

r360979 erroneously assumed that the lowest mapping in an address space
would be a file mapping, but of course this is not true in general.

Reported and tested by: Frederic Chardon <chardon.frederic@gmail.com>
MFC after: 3 days

librtld_db: Fix shlib mapping offsets.

kve_offset gives the offset into the backing file, which is not what we
want since different segments may map the same page. Use the base of
the mapping to determine the offset exported by librtld_db instead.

PR: 244732
Reported by: Jenkins, Nicolò Mazzucato <nicomazz97@gmail.com>
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation

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.

Avoid double-closing an fd if elf_begin() fails.

Reported by: Miles Ohlrich <miles.ohlrich@isilon.com>
MFC after: 1 week
Sponsored by: Dell EMC Isilon

Fix style bugs and remove trailing whitespace in libproc and librtld_db.

MFC after: 1 week

librtld_db: Use the auxv to figure out where to look up loader symbols.

Previously, librtld_db just hardcoded /libexec/ld-elf.so, which isn't
correct for processes that aren't using the native ABI. With this change,
librtld_db can be used to inspect non-native processes; in particular,
dtrace -c now works for 32-bit executables on amd64.

MFC after: 1 month

Hook up support for userland CTF support in DTrace. This required some
modifications to libproc to support fetching the CTF info for a given file.

With this change, dtrace(1) is able to resolve type info for function and
USDT probe arguments, and function return values. In particular, the args[n]
syntax should now work for referencing arguments of userland probes,
provided that the requisite CTF info is available.

The uctf tests pass if the test programs are compiled with CTF info. The
current infrastructure around the DTrace test suite doesn't support this
yet.

Differential Revision: https://reviews.freebsd.org/D891
MFC after: 1 month
Relnotes: yes
Sponsored by: EMC / Isilon Storage Division

Handle the different event types properly in rd_event_addr(). In particular,
with r265456 _r_debug_postinit can be used for RD_POSTINIT events. rtld(1)
uses r_debug_state for dl state transitions, so we use its address for
RD_DLACTIVITY events.

MFC after: 2 weeks

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

Import the librtld_db library. This is needed by userland DTrace.
This is not yet enabled in the build because I also need to import a new
version of libproc.

Sponsored by: The FreeBSD Foundation