Update libgomp.texi's OpenMP implementation status.
The 5.1 changes are taken from Jakub's comment at
https://gcc.gnu.org/pipermail/gcc-patches/2022-September/602639.html
(sorry for taking that long to incorporate those).

It also adds TR11. I don't think we will work any time soon
on TR11 – possibly except for clarifications.

OK for mainline?

Tobias

PS: Albeit sometimes there is a fine border between clarification and
larger new feature. For instance,
* implicitly declared reduction identifiers for arbitrary C++ classes - or
* how to handle implicit 'declare target' with declare variant and (no)host
   selectors.
(The TR11 wording implies that the former is an old feature, while the latter
is implied by the OpenMP 5.2 examples document, albeit an issue to clarify
this in TR12 exists. For the latter: https://gcc.gnu.org/PR106316 + OpenMP Spec Issue 3416.)
-----------------
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