Revert "Build libc++ and libc++abi with -std=c++20"

This reverts commit aea3a572a01844fdf4b4137d2b0c1fad90f70aab.

Reason for revert: Broke compile on linux-gcc-rel bot

g++: error: unrecognized command line option ‘-std=c++20’; did you mean ‘-std=c++03’?

Original change's description:
> Build libc++ and libc++abi with -std=c++20
> This changed upstream a while ago
> (, and as of
> this commit it's required to build libcxxabi:
> Generally, we require the same -std= flag across all of chromium.
> Given that this is a low-level external library, make an exception
> for just this library. (It also used c++17 before the rest, for the
> same reasons.) No other target should do this.
> Bug: 1298070
> Change-Id: I6767464dfea1ae3b61224563da96be5dd08bd702
> Reviewed-on:
> Commit-Queue: Nico Weber <>
> Auto-Submit: Nico Weber <>
> Reviewed-by: Hans Wennborg <>
> Commit-Queue: Hans Wennborg <>
> Cr-Commit-Position: refs/heads/main@{#971961}

Bug: 1298070
Change-Id: Ia1d1c7e7923af63ea409d128aa842c1140fc8a58
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Owners-Override: Marijn Kruisselbrink <>
Auto-Submit: Marijn Kruisselbrink <>
Commit-Queue: Rubber Stamper <>
Bot-Commit: Rubber Stamper <>
Cr-Commit-Position: refs/heads/main@{#971963}
GitOrigin-RevId: dca2c86a4bbb1664d65a810b856677c05f3e3ff1
1 file changed