allow build without internet by skipping the update step of externall…

…y added project covariance_geometry_cpp by default (optionally it can be enable with cmake arguments; this does not prevent downloading the library in case it is not present at all)

fuse_core/CMakeLists.txt

@@ -131,13 +131,16 @@ if(CATKIN_ENABLE_TESTING)
   include(ExternalProject)
   find_package(Git REQUIRED)
 
+  set(FUSE_CORE_UPDATE_DISCONNECTED ON CACHE BOOL "Set to OFF to force check for updates of covariance_geometry_cpp")
+
   externalproject_add(
     covariance_geometry_cpp
     PREFIX ${CMAKE_CURRENT_BINARY_DIR}/covariance_geometry_cpp
     GIT_REPOSITORY https://github.com/ARTI-Robots/covariance_geometry.git
     GIT_TAG master
     TIMEOUT 10
     UPDATE_COMMAND ${GIT_EXECUTABLE} pull
+    UPDATE_DISCONNECTED ${FUSE_CORE_UPDATE_DISCONNECTED}
     CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${CMAKE_CURRENT_BINARY_DIR}/covariance_geometry_cpp/src
     LOG_DOWNLOAD ON
   )