update clang to 17.0.2-2 from Msys2 in preparation for building our own
smaller clang for ARM64.

Signed-off-by: Matthias Aßhauer <mha1993@live.de>

Msys2 builds pretty versatile Clang and LLVM packages with LLVM backends
to cross compile for various target architectures. That comes at the
cost of big binaries, that challenge how we manage the Git for Windows
SDK[1]. But for Git for Windows we don't need all of this. We only need
a Clang that can compile ARM64 binaries on ARM64.

[1] git-for-windows/git-sdk-arm64#7

Signed-off-by: Matthias Aßhauer <mha1993@live.de>

We'll need to update our clang when Msys2 updates theirs and reapply our
customisations every time, so a script makes this job less tedious and
leaves no room to miss a step of the process.
This script performs the same steps as the previous two commits. (it
was used to generate the files for those)

Signed-off-by: Matthias Aßhauer <mha1993@live.de>