MFC r335213: ldd: reference readelf instead of objdump in warning message

We have an obsolete GNU objdump 2.17.50 in the base system, which will
be removed in the future. Suggest readelf(1) for examining ELF files
instead; for most use cases it is the preferred tool anyhow.

PR: 229046
Sponsored by: The FreeBSD Foundation

MFC r326276:

various: general adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified 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.

No functional change intended.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Avoid double close() of a file descriptor.

CID: 1006089
Found with: Coverity Prevent(tm)
MFC after: 1 week

Fix clang warnings.

Approved by: philip (mentor)

The type of some aout header types changed to uint_32, so now we need
to cast to long before printing. While I'm here, raise WARNS to 6.

Fix a few WARNS:
1) Include string.h for strcpy.
2) Don't make duplicate declaration of dump_file, we now include extern.h.
3) Help out with some constness.
4) Cast to slightly better types in some comparisons.

Initiate deorbit burn for the i386-only a.out related support. Moves are
under way to move the remnants of the a.out toolchain to ports. As the
comment in src/Makefile said, this stuff is deprecated and one should not
expect this to remain beyond 4.0-REL. It has already lasted WAY beyond
that.

Notable exceptions:
gcc - I have not touched the a.out generation stuff there.
ldd/ldconfig - still have some code to interface with a.out rtld.
old as/ld/etc - I have not removed these yet, pending their move to ports.
some includes - necessary for ldd/ldconfig for now.

Tested on: i386 (extensively), alpha

Warns; ANSIfy, constify and move declarations into a common header.

Include <arpa/inet.h> for prototype of ntohl() used in the N_BADMAG()
macro.

Fix long format mismatch with int arg

* include/elf.h has been repo copied to include/elf-hints.h, and it no
longer includes machine/elf.h.
* consumers of elf.h now use the minimalist elf header possible.

This change is motivated by Binutils 2.11.0 and too much clashing over
our base elf headers and the Binutils elf headers.

Add rcsid. Remove unused #include. Remove error() definition and replace
with warn().

$Id$ -> $FreeBSD$

Make ldd work on alpha.

Add ELF support.

In the "ldd -v" output, display the N_AUX information for each
symbol. It indicates whether the symbol refers to a function or a
data object.

Touch up the code that implements "ldd -v".

Bring the style of sods.c into better conformance. Add code to
print the contents of each datum being relocated. Correct the logic
that distinguishes between programs, shared libraries, and object
files. Make the entire program "-Wall" clean.

Revert $FreeBSD$ to $Id$

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

For "ldd -v", print shared object dependencies that were specified as
pathnames (rather than as "-lfoo") correctly.
Closes PR bin/2404.

Incorporate John Polstra's sods.c display of the details about the
dynamic linking information in the executable. It's quite extensive.
It's connected to ldd's (new) -v option.