cmake HAS_CXX_STD examples

ElektraInitiative/libelektra scripts/cmake/ElektraCompiling.cmake :29 

check_cxx_compiler_flag (${CXX_STD} HAS_CXX_STD)

ElektraInitiative/libelektra scripts/cmake/ElektraCompiling.cmake :33 

endif (NOT HAS_CXX_STD)