cmake HAVE_SIGSET examples

alibaba/AliSQL configure.cmake :580 

CHECK_FUNCTION_EXISTS (sigset HAVE_SIGSET)

arkdb/arkproxy configure.cmake :393 

CHECK_FUNCTION_EXISTS (sigset HAVE_SIGSET)

alibaba/AliSQLBackup configure.cmake :495 

CHECK_FUNCTION_EXISTS (sigset HAVE_SIGSET)