message: [CMake] Fix standalone build for debugserver on macOS
  Summary:
  Quick-fix to avoid CMake config issue:
  ```
  CMake Error at /path/to/lldb/cmake/modules/AddLLDB.cmake:116 (add_dependencies):
  Cannot add target-level dependencies to non-existent target "lldb-suite".
  ```
  Reviewers: xiaobai, beanz
  Subscribers: mgorny, lldb-commits
diff: @@ -14,6 +14,11 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
  set(LLDB_SOURCE_DIR "${CMAKE_SOURCE_DIR}/../../")
  include_directories(${LLDB_SOURCE_DIR}/include)
  +
  + # lldb-suite is a dummy target that encompasses all the necessary tools and
  + # libraries for building a fully-functioning liblldb.
  + add_custom_target(lldb-suite)
  + set(LLDB_SUITE_TARGET lldb-suite)
  endif()
  add_subdirectory(source)
  