Use CMAKE_CXX_STANDARD setting for inner CTK build and sub-projects

CMake/ctkBlockCheckDependencies.cmake

@@ -44,6 +44,7 @@ if(CTK_SUPERBUILD)
       -DCMAKE_CXX_COMPILER:FILEPATH=${CMAKE_CXX_COMPILER}
       -DCMAKE_C_FLAGS:STRING=${ep_common_c_flags}
       -DCMAKE_CXX_FLAGS:STRING=${ep_common_cxx_flags}
+      -DCMAKE_CXX_STANDARD:STRING=${CMAKE_CXX_STANDARD}
       -DCMAKE_INSTALL_PREFIX:PATH=${ep_install_dir}
       -DCMAKE_PREFIX_PATH:STRING=${CMAKE_PREFIX_PATH}
       -DBUILD_TESTING:BOOL=OFF

SuperBuild.cmake

@@ -43,6 +43,7 @@ ExternalProject_Add(${proj}
     -DCMAKE_C_COMPILER:FILEPATH=${CMAKE_C_COMPILER}
     -DCMAKE_CXX_COMPILER:FILEPATH=${CMAKE_CXX_COMPILER}
     -DCMAKE_CXX_FLAGS_INIT:STRING=${CMAKE_CXX_FLAGS_INIT}
+    -DCMAKE_CXX_STANDARD:STRING=${CMAKE_CXX_STANDARD}
     -DCMAKE_C_FLAGS_INIT:STRING=${CMAKE_C_FLAGS_INIT}
     -DCMAKE_INSTALL_PREFIX:PATH=${CMAKE_INSTALL_PREFIX}
   SOURCE_DIR ${CTK_SOURCE_DIR}