Add llvm 14 auto-detection

[am11]

Tested with:

$ docker build -t debian-llvm14 - << EOF
FROM debian:latest

RUN apt update && apt install -y wget lsb-release gpg software-properties-common locales

RUN wget https://apt.llvm.org/llvm.sh && bash ./llvm.sh 14 all

RUN sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && locale-gen

ENV LC_ALL en_US.UTF-8 

RUN apt install -y liblttng-ust-dev libicu-dev libssl-dev libkrb5-dev libz-dev cmake
EOF

$ docker run -v$(pwd):/runtime debian-llvm14 /runtime/build.sh -c Release

[am11]

cc @jkotas, @janvorli

[jkotas]

Thanks