Newlib's .texi docs - outdated version number/date

[Tobias Burnus <tobias@codesourcery.com>]

Someone over here stumbled over the version/date mismatch between what is shown
in the libc/libm manuals - and what is the current newlib release.

I think it makes sense to bump the version + date of the two files for the release,
alongside the other version bumps done for the release. Namely, I think it should have
been part of the commit:
   commit 9e09d6ed83cce4777a5950412647ccc603040409 (tag: newlib-4.3.0)
   Bump up newlib to 4.3.0

Currently, there is the following (I think the first one is okayish
as it does not refer to the newlib version):

libgloss/doc/porting.texi
   @subtitle Spring 1995

newlib/libc/libc.texi
   @subtitle @code{libc} 2.5.0
   @subtitle December 2016

newlib/libm/libm.texi
   @subtitle @code{libm} 2.5.0
   @subtitle December 2016

The last textual change to libc was mid 2021, the last janitorial/re-org changes were
at the end of last year. Thus, blindly bumping the version/date seems to be at least more
consistent than not updating it at all.

Thoughts?

Tobias

PS: Namely, something like the following. (Ignoring (C) lines etc.)

--- a/newlib/libc/libc.texi
+++ b/newlib/libc/libc.texi
@@ -72,2 +72,2 @@ into another language, under the above conditions for modified versions.
-@subtitle @code{libc} 2.5.0
-@subtitle December 2016
+@subtitle @code{libc} 4.3.0
+@subtitle January 2023

--- a/newlib/libm/libm.texi
+++ b/newlib/libm/libm.texi
@@ -49,2 +49,2 @@ into another language, under the above conditions for modified versions.
-@subtitle @code{libm} 2.5.0
-@subtitle December 2016
+@subtitle @code{libm} 4.3.0
+@subtitle January 2023

-----------------
Siemens Electronic Design Automation GmbH; Anschrift: Arnulfstraße 201, 80634 München; Gesellschaft mit beschränkter Haftung; Geschäftsführer: Thomas Heurung, Frank Thürauf; Sitz der Gesellschaft: München; Registergericht München, HRB 106955