small cleanup
cleanup: wsrep_check_opts
restore and fix wsrep status variables
cleanup: remove OPT_WSREP_START_POSITION and OPT_WSREP_SST_AUTH

there is no reason to initialize wsrep start position
and auth from inside the get_one_option() callback
cleanup: introduce CF_SKIP_WSREP_CHECK

remove if() over many COM_xxx values