Revert "Revert clang update, got too many weird issues."

This reverts commit f37c5aa5b8.

We now know that it was not the clang version that was the problem, it
was the linker (mold)

Dockerfile-ubuntu2204

     apt-get -y install vim gdb strace patch && \
     \
     apt update -y && \
-    apt-get install -y clang-14 clang-tidy-14 libclang-14-dev clangd-14 lldb-14 lld-14 clangd-14 && \
-    apt-get install -y libc++-14-dev libc++-14-dev clang-format-14 && \
+    apt-get install -y clang-15 clang-tidy-15 libclang-15-dev clangd-15 lldb-15 lld-15 clangd-15 && \
+    apt-get install -y libc++-15-dev libc++-15-dev clang-format-15 clang-tidy-15 && \
     \
     rm -rf /var/lib/apt/lists/*
 
 RUN /emsdk/upstream/emscripten/em++ -s WASM=1 -s USE_SDL=2 -s USE_SDL_TTF=2 -O3 /dev/null || true
 
 # Fix some weird linker issue CAF build runs into. (fails to link -lc++abi)
-RUN cp -prv /usr/lib/llvm-14/lib/libc++abi.so.1.0 /usr/lib/llvm-14/lib/libc++abi.so
+RUN cp -prv /usr/lib/llvm-15/lib/libc++abi.so.1.0 /usr/lib/llvm-15/lib/libc++abi.so
 
 # EDIT: no longer needed!
 # RUN cp -prv /usr/lib/llvm-14/lib/libunwind.so.1.0 /usr/lib/llvm-14/lib/libunwind.so

switch-to-latest-clang

 set +e
 set -o pipefail
 
-update-alternatives --install /usr/bin/c++ c++ /usr/bin/clang++-14 40 > /tmp/.switch-to-clang.stdout
-update-alternatives --install /usr/bin/cc cc /usr/bin/clang-14 40 >>  /tmp/.switch-to-clang.stdout
-update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-14 40 >>  /tmp/.switch-to-clang.stdout
-update-alternatives --install /usr/bin/clang clang /usr/bin/clang-14 40 >>  /tmp/.switch-to-clang.stdout
-update-alternatives --install /usr/bin/ld ld /usr/bin/ld.lld-14 40 >>  /tmp/.switch-to-clang.stdout
+update-alternatives --install /usr/bin/c++ c++ /usr/bin/clang++-15 40 > /tmp/.switch-to-clang.stdout
+update-alternatives --install /usr/bin/cc cc /usr/bin/clang-15 40 >>  /tmp/.switch-to-clang.stdout
+update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-15 40 >>  /tmp/.switch-to-clang.stdout
+update-alternatives --install /usr/bin/clang clang /usr/bin/clang-15 40 >>  /tmp/.switch-to-clang.stdout
+update-alternatives --install /usr/bin/ld ld /usr/bin/ld.lld-15 40 >>  /tmp/.switch-to-clang.stdout
 
 echo compiler set to: $(readlink /etc/alternatives/c++)