CMake 4 no longer sets the CMAKE_OSX_SYSROOT variable by default, causing the lldb build to fail after all GitHub-hosted runners have been upgraded to CMake 4. As a workaround, the variable is set using CMake command line options. There is a PR to fix this issue in the llvm-project: https://github.com/llvm/llvm-project/pull/138020. We might want to remove this workaround after that PR has been merged.