[client] Fix a kudu c++ client bug when using replica_selection policy

At c++ client side, the replica_selection policy (LEADER_ONLY and
CLOSEST_REPLICA) is not working. Eg command: 'kudu perf table_scan
$master_list $table -columns=id,name -num_threads=4 -nofill_cache
-replica_selection="LEADER"', but the real replica_selection policy
is CLOSEST_REPLICA.

The patch fixes the bug in client library and adds unit tests.

Change-Id: I413f99b6a0b6082c5453358b8333913e4c6264c2
Reviewed-on: http://gerrit.cloudera.org:8080/18877
Reviewed-by: Yuqi Du <shenxingwuying@gmail.com>
Tested-by: Kudu Jenkins
Reviewed-by: Yifan Zhang <chinazhangyifan@163.com>
5 files changed