cmake HAVE_SIGWAIT examples

alibaba/AliSQL configure.cmake :576 

CHECK_FUNCTION_EXISTS (sigwait HAVE_SIGWAIT)

arkdb/arkproxy configure.cmake :392 

CHECK_FUNCTION_EXISTS (sigwait HAVE_SIGWAIT)

alibaba/AliSQLBackup configure.cmake :491 

CHECK_FUNCTION_EXISTS (sigwait HAVE_SIGWAIT)