message: [CMake] Add missing dep for unified builds
  The target of the symlink needs to exist too.
diff: @@ -168,7 +168,7 @@ set(lib_dir "${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/lib${LLVM_LIBDIR_SUFFIX}")
  set(CLANG_RESOURCE_PATH "${LLDB_PATH_TO_SWIFT_BUILD}/lib${LLVM_LIBDIR_SUFFIX}/swift/clang")
  set(clang_headers_target ${CLANG_RESOURCE_PATH}/include)
  if(NOT LLDB_BUILT_STANDALONE)
  - set(clang_headers_target symlink_clang_headers)
  + set(clang_headers_target clang-headers symlink_clang_headers)
  endif()
  # Copy the clang resource directory.
  