Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r245133:
Only assign the environ in the startup code when environ is NULL.

Note that this is not the merge, but a reimplementation of the fix,
done for the not-consolidated code in the stable/9.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Let all .c and .S files under lib/csu consistently use the __FBSDID()
macro for identification, instead of several different hand-rolled
variants (plain .ident, .ascii, etc).

Properly declare non-extern functions in crt1

Also move the declarations after __progname consistently to
make the distinction clearer.

Reviewed by: jmallett
Approved by: ed (co-mentor)

Add support for TLS in statically linked programs.

make these more useful for lint(1). Minor diff-reductions while I'm
about it.

The main reason for this is to reduce diffs between all the crt1.c's.

Assembler macros are tidied up and made as similar as sanely possible.
The macros are translated into C (__inline static) functions for lint.

Declaration orders are made the same.
Declarations are all ISOfied and tidied up.

Comment contents have gratuitous diffs removed.

The net result is a bunch of crt1.c's that are 90% the same.
It may be possible to now encapsulate the differences in one
MD header, and have only one MI crt1.c file (although the macros
to do this may be ugly).

Helpful comments by: obrien, bde
Alpha tested by: des
i386-elf tested by: markm

Do not use __progname directly (except in [gs]etprogname(3)).
Also, make an internal _getprogname() that is used only inside
libc. For libc, getprogname(3) is a weak symbol in case a
function of the same name is defined in userland.

Remove prototype, no other crt1.c has or needs it.

Remove __P() usage.

Remove __P() usage.

Minor style(9) nit + utilize ELF features for the FreeBSD ID.

Removed duplicate VCS ID tags, as per style(9).

Fix compilation errors by adding forward declarations and fix typo.

PowerPC version of the C runtime support.

This is an amalgamation of the NetBSD macppc crt0.c (which the copyright
reflects) and the FreeBSD/Alpha crt1.c.