LDC 1.42.0-beta2

[kinke]

Glad to announce the second beta for LDC 1.42. Major changes 
since beta1:

* Based on recent DMD/Phobos `stable` with important D 2.112.0 
regression fixes.
* The prebuilt packages now use LLVM 21.
* New `--fdebug-prefix-map` command-line option, analogous to 
clang.

Full release log and downloads: 
https://github.com/ldc-developers/ldc/releases/tag/v1.42.0-beta2

Please help test, and thanks to all contributors & sponsors!