message: example: link to thread lib
diff: @@ -7,6 +7,9 @@ add_definitions("-std=c++11 -Wall -Wextra -Werror")
  # Add DEBUG define for Debug target
  set(CMAKE_CXX_FLAGS_DEBUG "-DDEBUG")
  +# This finds thread libs on Linux, Mac, and Windows.
  +find_package(Threads REQUIRED)
  +
  include_directories(
  # Not needed if installed system-wide
  ../install/include
  @@ -20,4 +23,5 @@ target_link_libraries(takeoff_and_land
  ${CMAKE_SOURCE_DIR}/../install/lib/libdronelink.a
  # If installed system-wide:
  # dronelink
  + ${CMAKE_THREAD_LIBS_INIT}
  )
  