…acktraces (#5375)

## Description

Pull request was inspired by the need to debug lock problems when
working on #5352.

As far as I'm aware, only macOS has `-Werror=thread-safety` as part of
its default `CXXFLAGS` despite the capability being present on Linux as
well. This PR introduces thread safety checks for that into our thread
sanitizer build.

Additionally, since we're using Clang, something that on first glimpse,
appears to be something that `stacktraces.cpp` isn't happy with, due to
`-Wl,-wrap` being available only on GCC, that no longer seems to be the
case, since the version of Clang with comes with `focal`, its `lld`
_does_ have support for `-wrap` (see [man page for `lld` on
`focal`](https://manpages.ubuntu.com/manpages/focal/en/man1/lld.1.html)).

The current `stable` version of Clang/LLVM is 15, at the time of this
pull request (see https://apt.llvm.org/) but `focal` ships with an older
version, requiring us to use the official LLVM APT repository. I feel we
should be testing with recent compilers alongside the ones shipped by
LTS distributions.

Certain bugs are only made apparent when testing on rolling release
distros or distros that have faster update cycles, like Fedora (see
#5295 for an illustration of that),
which ship with more recent compilers. Until we overhaul our CI systems
to test using those distros directly (our current infrastructure is
centered around using a "development image" with an LTS distro as the
base), this is the best we can do.

A similar pull request testing against the latest GCC stable will be
welcome as that is currently outside the scope of this PR as the changes
made were to make sure that builds were operating as expected on
Clang/LLVM 15.

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Co-authored-by: UdjinM6 <[email protected]>