Roll libc++ from b4596f1d2b9d to f48ac93bb382 (14 revisions)

https://chromium.googlesource.com/external/github.com/llvm/llvm-project/libcxx.git/+log/b4596f1d2b9d..f48ac93bb382

2025-12-12 hghristov.rmm@gmail.com [libc++][filesystem] Applied `[[nodiscard]]` (#171085)
2025-12-12 hghristov.rmm@gmail.com [libc++][optional] Applied `[[nodiscard]]` (#170045)
2025-12-12 hghristov.rmm@gmail.com [libc++][format] Applied `[[nodiscard]]` to more classes (#170808)
2025-12-12 hghristov.rmm@gmail.com [libc++][set] Applied `[[nodiscard]]` (#169982)
2025-12-11 ldionne.2@gmail.com [libc++] Simplify how we install test-suite dependencies (#171504)
2025-12-11 ldionne.2@gmail.com [runtimes] Modernize installation targets (#171677)
2025-12-11 ldionne.2@gmail.com [libc++] Fix incorrect install component for the libc++ linker script (#171663)
2025-12-11 ldionne.2@gmail.com [libc++][NFC] Wrap line endings for clang-tidy tests (#171688)
2025-12-11 nikolasklauser@berlin.de [libc++] Merge the segmented iterator code for {copy,move}_backward (#165160)
2025-12-11 nikolasklauser@berlin.de [libc++] Remove initializer_list specific optimization in __tree (#169413)
2025-12-11 nikolasklauser@berlin.de [libc++] Make std::allocator always trivially default constructible (#169914)
2025-12-11 nikolasklauser@berlin.de [libc++] Add `__find_end` optimizations back (#171374)
2025-12-11 ldionne.2@gmail.com [libc++] Don't instantiate __split_buffer with an allocator reference (#171651)
2025-12-10 aidengrossman@google.com [libc++][Github] Bump Runner Version to v2.330.0 (#168753)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/libcxx-chromium
Please CC hans@chromium.org,thakis@chromium.org on the revert to ensure that a human
is aware of the problem.

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To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Tbr: hans@chromium.org,thakis@chromium.org
Change-Id: Id5351d6c6d7c769687097fd3511efd71c7b0e733
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7255614
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1557985}
NOKEYCHECK=True
GitOrigin-RevId: 4c3ce49bc35151506dafd0f0c492af3e60ffe64c