message: [CMake] Don't modify LLVM_DISTRIBUTION_COMPONENTS if it's not set
  Don't try to remove debugserver from LLVM_DISTRIBUTION_COMPONENTS if the
  list is not set.
diff: @@ -118,8 +118,10 @@ if(CMAKE_HOST_APPLE)
  COMMENT "Copying the system debugserver to LLDB's binaries directory for testing.")
  # The custom target for the system debugserver has no install target, so we
  # need to remove it from the LLVM_DISTRIBUTION_COMPONENTS list.
  + if (LLVM_DISTRIBUTION_COMPONENTS)
  list(REMOVE_ITEM LLVM_DISTRIBUTION_COMPONENTS debugserver)
  set(LLVM_DISTRIBUTION_COMPONENTS ${LLVM_DISTRIBUTION_COMPONENTS} PARENT_SCOPE)
  + endif()
  message(STATUS "LLDB tests use out-of-tree debugserver: ${system_debugserver_path}")
  list(APPEND LLDB_TEST_COMMON_ARGS --out-of-tree-debugserver)
  elseif(TARGET debugserver)
  