Roll libc++ from af4386908c37 to 8e870711923d (1 revision)

This removes a public header, which requires updating all module
GN files. I updated them by running:

    build/modules/modularize/modularize.py --no-cache

on a Linux box with `target_os = [ 'android', 'win', 'mac', 'fuchsia' ]`
in .gclient.

I manually updated buildtools/third_party/libc++/BUILD.gn to look
like the generated Mac version, as that's used on iOS and on macOS
without a hermetic sysroot.

Depends on
https://chromium-review.googlesource.com/c/chromium/src/+/7785076

https://chromium.googlesource.com/external/github.com/llvm/llvm-project/libcxx.git/+log/af4386908c37..8e870711923d

2026-01-19 iana@apple.com [libc++] Remove libc++'s <float.h> (#175849)

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.

To file a bug in Chromium: https://bugs.chromium.org/p/chromium/issues/entry

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

Bug: 503250165
Change-Id: I3046a8e562c7ef98d7b1933ec651fd9ea5bc72ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/7494039
Owners-Override: Nico Weber <thakis@chromium.org>
Reviewed-by: Arthur Eubanks <aeubanks@google.com>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1619707}
NOKEYCHECK=True
GitOrigin-RevId: ffd3856b7f2ac4643be3383fbd93e76cea4aabc1