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)

Implement .init and .fini.

Add support for TLS in statically linked programs.

C runtime support for FreeBSD/arm.