message: disable installation of GTest and GMock
diff: # settings on Windows
  set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
  +set(INSTALL_GMOCK OFF CACHE BOOL "" FORCE)
  +set(INSTALL_GTEST OFF CACHE BOOL "" FORCE)
  +
  load_git_package(gtest
  "https://github.com/google/googletest.git"
  "master")
  