[libc++] Update some C++23 statuses to "Nothing to do" or "Complete" (#99621)

Summary:
- [P2160R1][] "Locks lock lockables"
- [P2212R2][] "Relax Requirements for `time_point::clock`"
- [P1675R2][] "`rethrow_exception` must be allowed to copy"
- [P2340R1][] "Clarifying the status of the 'C headers'"
- [P2460R2][] "Relax requirements on `wchar_t` to match existing
practices"

Are all papers that change wording without changing implementation
behaviour.

Additionally, [P2736R2][] "Referencing The Unicode Standard", is an
already complete paper in 19.0 (as of [LLVM-86543][])

[P2160R1]: https://wg21.link/p2160r1
[P2212R2]: https://wg21.link/p2212r2
[P1675R2]: https://wg21.link/p1675r2
[P2340R1]: https://wg21.link/p2340r1
[P2460R2]: https://wg21.link/p2460r2
[P2736R2]: https://wg21.link/p2736r2
[LLVM-86543]: #86543

Test Plan: 

Reviewers: 

Subscribers: 

Tasks: 

Tags: 


Differential Revision: https://phabricator.intern.facebook.com/D60251122

Author: strega-nil

libcxx/docs/Status/Cxx23Papers.csv

@@ -6,9 +6,9 @@
 "","","","","","",""
 "`P1682R3 <https://wg21.link/P1682R3>`__","LWG","std::to_underlying for enumerations","February 2021","|Complete|","13.0"
 "`P2017R1 <https://wg21.link/P2017R1>`__","LWG","Conditionally borrowed ranges","February 2021","|Complete|","16.0","|ranges|"
-"`P2160R1 <https://wg21.link/P2160R1>`__","LWG","Locks lock lockables","February 2021","",""
+"`P2160R1 <https://wg21.link/P2160R1>`__","LWG","Locks lock lockables","February 2021","Nothing to do",""
 "`P2162R2 <https://wg21.link/P2162R2>`__","LWG","Inheriting from std::variant","February 2021","|Complete|","13.0"
-"`P2212R2 <https://wg21.link/P2212R2>`__","LWG","Relax Requirements for time_point::clock","February 2021","",""
+"`P2212R2 <https://wg21.link/P2212R2>`__","LWG","Relax Requirements for time_point::clock","February 2021","Nothing to do",""
 "`P2259R1 <https://wg21.link/P2259R1>`__","LWG","Repairing input range adaptors and counted_iterator","February 2021","","","|ranges|"
 "","","","","","",""
 "`P0401R6 <https://wg21.link/P0401R6>`__","LWG","Providing size feedback in the Allocator interface","June 2021","|Complete|","15.0"
@@ -29,12 +29,12 @@
 "`P1072R10 <https://wg21.link/P1072R10>`__","LWG","``basic_string::resize_and_overwrite``","October 2021","|Complete|","14.0"
 "`P1147R1 <https://wg21.link/P1147R1>`__","LWG","Printing ``volatile`` Pointers","October 2021","|Complete|","14.0"
 "`P1272R4 <https://wg21.link/P1272R4>`__","LWG","Byteswapping for fun&&nuf","October 2021","|Complete|","14.0"
-"`P1675R2 <https://wg21.link/P1675R2>`__","LWG","``rethrow_exception`` must be allowed to copy","October 2021","",""
+"`P1675R2 <https://wg21.link/P1675R2>`__","LWG","``rethrow_exception`` must be allowed to copy","October 2021","Nothing to do",""
 "`P2077R3 <https://wg21.link/P2077R3>`__","LWG","Heterogeneous erasure overloads for associative containers","October 2021","",""
 "`P2251R1 <https://wg21.link/P2251R1>`__","LWG","Require ``span`` & ``basic_string_view`` to be Trivially Copyable","October 2021","|Complete|","14.0"
 "`P2301R1 <https://wg21.link/P2301R1>`__","LWG","Add a ``pmr`` alias for ``std::stacktrace``","October 2021","",""
 "`P2321R2 <https://wg21.link/P2321R2>`__","LWG","``zip``","October 2021","|In Progress|","","|ranges|"
-"`P2340R1 <https://wg21.link/P2340R1>`__","LWG","Clarifying the status of the 'C headers'","October 2021","",""
+"`P2340R1 <https://wg21.link/P2340R1>`__","LWG","Clarifying the status of the 'C headers'","October 2021","Nothing to do",""
 "`P2393R1 <https://wg21.link/P2393R1>`__","LWG","Cleaning up ``integer``-class types","October 2021","",""
 "`P2401R0 <https://wg21.link/P2401R0>`__","LWG","Add a conditional ``noexcept`` specification to ``std::exchange``","October 2021","|Complete|","14.0"
 "","","","","","",""
@@ -74,7 +74,7 @@
 "`P2438R2 <https://wg21.link/P2438R2>`__","LWG","``std::string::substr() &&``","July 2022","|Complete|","16.0"
 "`P2445R1 <https://wg21.link/P2445R1>`__","LWG","``forward_like``","July 2022","|Complete|","16.0"
 "`P2446R2 <https://wg21.link/P2446R2>`__","LWG","``views::as_rvalue``","July 2022","|Complete|","16.0","|ranges|"
-"`P2460R2 <https://wg21.link/P2460R2>`__","LWG","Relax requirements on ``wchar_t`` to match existing practices","July 2022","",""
+"`P2460R2 <https://wg21.link/P2460R2>`__","LWG","Relax requirements on ``wchar_t`` to match existing practices","July 2022","Nothing to do",""
 "`P2465R3 <https://wg21.link/P2465R3>`__","LWG","Standard Library Modules ``std`` and ``std.compat``","July 2022","|Complete|","19.0",""
 "`P2467R1 <https://wg21.link/P2467R1>`__","LWG","Support exclusive mode for ``fstreams``","July 2022","|Complete|","18.0",""
 "`P2474R2 <https://wg21.link/P2474R2>`__","LWG","``views::repeat``","July 2022","|Complete|","17.0","|ranges|"
@@ -120,4 +120,4 @@
 "`P2614R2 <https://wg21.link/P2614R2>`__","LWG", "Deprecate ``numeric_limits::has_denorm``","February 2023","|Complete|","18.0",""
 "`P2588R3 <https://wg21.link/P2588R3>`__","LWG", "``barrier``’s phase completion guarantees","February 2023","","",""
 "`P2763R1 <https://wg21.link/P2763R1>`__","LWG", "``layout_stride`` static extents default constructor fix","February 2023","","",""
-"`P2736R2 <https://wg21.link/P2736R2>`__","CWG","Referencing The Unicode Standard","February 2023","","","|format|"
+"`P2736R2 <https://wg21.link/P2736R2>`__","CWG","Referencing The Unicode Standard","February 2023","Complete","19.0","|format|"