vlc-debian-llvm-ucrt/msvcrt: update to LLVM 15

Corresponds to https://github.com/mstorsjo/llvm-mingw/releases/tag/20220906

This may solve the issue codeview debugging using crashing in ffmpeg when compiling for ARM. Doing the same build in my LLVM-mingw 15 UCRT with the same compilation parameters worked for me.