LLVM update to 19

[Adam <adam%netbsd.org@localhost>]

Following the new protocol, I'd like to update LLVM to 19. That includes:

* everything mentioned as "used by" in lang/llvm/version.mk
* include-what-you-use - update to 0.23
* qtcreator - update to 16.0.0 (thanks to @wiz for solving the RPATH problem)
* opencl-clang - update to 19.1.0
* pocl - needs to be patched - I've got the patches ready based on upstream pull request
* spirv-headers - update to 1.4.309.0
* spirv-llvm-translator - update to 19.1.7
* woboq_codebrowser - update to 2.1.20250221 (commit 9c819d5072dba9ba8eb07646d712b46229f7ecb5)
* zig - update to 0.14.0

So far everything (meaning meta-pkgs/bulk-test-llvm) seems to be building on NetBSD 10 x86_64 and aarch64, and macOS.

Any objections?

Kind regards,
Adam