state to the joiner

In mysqldump SST, if Galera nodes are started with --log-bin and
-log-slave-updates, the GTID sequence increases as the dump is
played on the joiner, leaving behind the donor.

This patch introduces a new mysqldump option --galera-sst-mode,
which if enabled, would

a) Add command to set off binary logging (log_bin=OFF).
b) Add command to set @@global.gtid_binlog_state to that
   of donor.

This will help in keeping the GTIDs consistent post-SST across
the nodes.