remove CMAKE_CXX_STANDARD since cmake 3.5.1 (Ubuntu 16.04) does not support "17" as a value yet

cmake/enable_latest_cxx_support.cmake

@@ -30,17 +30,14 @@ if(COMPILER_SUPPORTS_CXX17)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++17")
     set(${PROJECT_NAME}_CXX_FLAGS "${${PROJECT_NAME}_CXX_FLAGS} -std=c++17")
     set(${PROJECT_NAME}_CMAKE_CXX_FLAGS "${${PROJECT_NAME}_CMAKE_CXX_FLAGS} -std=c++17")
-    set(CMAKE_CXX_STANDARD 17)
 elseif(COMPILER_SUPPORTS_CXX14)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14")
     set(${PROJECT_NAME}_CXX_FLAGS "${${PROJECT_NAME}_CXX_FLAGS} -std=c++14")
     set(${PROJECT_NAME}_CMAKE_CXX_FLAGS "${${PROJECT_NAME}_CMAKE_CXX_FLAGS} -std=c++14")
-    set(CMAKE_CXX_STANDARD 14)    
 elseif(COMPILER_SUPPORTS_CXX11)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
     set(${PROJECT_NAME}_CXX_FLAGS "${${PROJECT_NAME}_CXX_FLAGS} -std=c++11")
     set(${PROJECT_NAME}_CMAKE_CXX_FLAGS "${${PROJECT_NAME}_CMAKE_CXX_FLAGS} -std=c++11")
-    set(CMAKE_CXX_STANDARD 11)
 elseif(COMPILER_SUPPORTS_CXX0X)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++0x")
     set(${PROJECT_NAME}_CXX_FLAGS "${${PROJECT_NAME}_CXX_FLAGS} -std=c++0x")