[libcxx-commits] [libcxx] [libc++][hardening] Rework how the assertion handler can be overridden. (PR #77883)

[Konstantin Varlamov via libcxx-commits]

var-const wrote:

> For the record, the CI was green at the time of merging except for the [Buildkite jobs](https://buildkite.com/llvm-project/libcxx-ci/builds/32957) which were still pending (specifically the Windows and FreeBSD jobs). I'll monitor their status and make sure to quickly address failures, if any (hopefully not).

Update: all the jobs finished [successfully](https://buildkite.com/llvm-project/libcxx-ci/builds/32957).

https://github.com/llvm/llvm-project/pull/77883