Without ADDITIONAL_CLEAN_FILES it reports an error:
Cleaning... ninja: error: remove(contrib/llvm/llvm/NATIVE): Directory not empty
ninja: error: remove(/bld/contrib/llvm/llvm/NATIVE): Directory not empty
0 files.
Note, that ADDITIONAL_CLEAN_FILES had been added since cmake 3.15.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>