Bump Clang version to 21

Initial AI Vector Index Support

• New Feature: First-time support for compiling AI vector index projects, including Faiss, DiskANN, and VSAG.
• New Dependencies: Introduced libaio and OpenBLAS (single-threaded) to support vector computations and asynchronous IO.

Notes:

• Even when using Clang, libgomp should be used instead of libomp, as libomp relies on a C++-specific ABI, which is incompatible with ClickHouse.
• When building shared libraries (.so), use libgomp.so. libgomp.a lacks PIC and is not suitable for PIC-based shared library builds.

This release fixes gcc OpenMP compilation issues in certain environments

Upgraded Toolchains

• GCC upgraded to 15

• Clang upgraded to 20

Compatibility Enhancements

• Removed dependency on __cxa_thread_atexit_impl, improving compatibility with older glibc.

1. Fix ClickHouse build
2. Add llvm openmp

1. Bootstrapped toolchain using Gentoo Prefix.
2. Upgraded to GCC 14 and Clang 19.

Remove untested musl implementations. sin is extremely slower than glibc.

Reported by @HappenLee

Now the Exodus tool has been replaced with a simple Perl script that recursively collects all DSO dependencies. Additionally, the aarch64 toolchain has been updated and is now available with LLVM-17. This change was necessary because LLVM-18 is broken in the upstream Ubuntu 18 aarch64 environment.

1. Update to LLVM-18 and cmake-3.29
2. Preliminary support for building ByConity

Upgrade to gcc 13 and llvm 17.