wsrep_sst_rsync.sh is_local_ip function can come to incorrect conclusion

The is_local_ip function now incorrectly identifies ip-addresses falling under the "127.0.0.0/8" netmask as non-local, although they certainly belong to the loopback interface. This problem was discovered and discussed in detail in the description of the MENT-1170 issue, however, this bug needs to be fixed for CS editions as well (because from my point of view, this is just an error in the script, and not a feature request for ES editions).