Build LLVM 16.0.6.

Author: elliottslaughter

.github/workflows/main.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: ['ubuntu-latest', 'ubuntu-24.04-arm', 'macos-13', 'macos-14', 'windows-2022']
-        llvm: ['17.0.6']
+        llvm: ['16.0.6']
     steps:
       - uses: actions/checkout@v4
       - run: ./main.sh