[CMake] Deduplicate `Halide_LLVM_VERSION` and `LLVM_PACKAGE_VERSION`#6646

Merged

alexreinking merged 1 commit intohalide:mainfrom

LebedevRI:cmake-dedup-llvm-version-vars

Mar 16, 2022

Commits on Mar 12, 2022

[CMake] Deduplicate `Halide_LLVM_VERSION` and `LLVM_PACKAGE_VERSION`
LebedevRI
committed