Roll libc++ from 9b27200e8219 to 7c70886f2550 (13 revisions)

https://chromium.googlesource.com/external/github.com/llvm/llvm-project/libcxx.git/+log/9b27200e8219..7c70886f2550

2023-10-27 ldionne.2@gmail.com [libc++] Fix incorrect length check in std::basic_filebuf
2023-10-27 ldionne.2@gmail.com [libc++] Make sure we implement and test LWG2280 properly (#67670)
2023-10-27 var-const@users.noreply.github.com [libc++] Fix flakiness in `atomic_notify_all.pass.cpp` (#70436)
2023-10-27 rajveer.developer@icloud.com [libc++] Fix _CopySegment helper in ranges::copy(join_view, out) when called in a static assertion context (#69593)
2023-10-27 vitalybuka@google.com Revert "[libc++][tests] Fix a few remaining instances of outdated static assertion regexes in our test suite"
2023-10-27 vitalybuka@google.com Fix typo in c07903aac7b9bc60d48f0381073285d79642cc3f
2023-10-27 vitalybuka@google.com [libc++abi] Disable test with a leaks
2023-10-26 zhangyin2018@iscas.ac.cn [libc++] <experimental/simd> Add assignment operator of simd reference (#70020)
2023-10-26 ldionne.2@gmail.com [libc++][NFC] Remove unused typedefs in filesystem::path helpers (#70331)
2023-10-26 tokarip@google.com [libc++] Optimize string operator[] for known large inputs (#69500)
2023-10-26 ldionne.2@gmail.com [libc++][tests] Fix a few remaining instances of outdated static assertion regexes in our test suite
2023-10-26 fsb4000@yandex.ru [libc++] Make sure std::declval() produces an error when ODR-used
2023-10-26 nikolasklauser@berlin.de [libc++] Add __small_buffer

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Tbr: hans@chromium.org,thakis@chromium.org
Change-Id: I371e06cc9aad630a337202619522305bc2b870fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4984702
Bot-Commit: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1216245}

• DEPS[diff]
• buildtools/deps_revisions.gni[diff]
• third_party/libc++/src[diff]