client: remove an unnecessary KUDU_NO_EXPORT
client: remove an unnecessary KUDU_NO_EXPORT

KuduSchemaBuilder::Data is already declared KUDU_NO_EXPORT in schema.h.

I verified that with this patch KuduSchemaBuilder::Data still isn't listed
in the output of "nm --defined -C -D lib/exported/libkudu_client.so".

Change-Id: Ib11424797401c8d2192b46f92de24e52a1fd8e79
Reviewed-on: http://gerrit.cloudera.org:8080/6019
Tested-by: Kudu Jenkins
Reviewed-by: Todd Lipcon <2c763d726a8c2f6afda9be7e0e56a2caa6bb5e6b@apache.org>

helifu/kudu,andrwng/kudu,andrwng/kudu,cloudera/kudu,InspurUSA/kudu,InspurUSA/kudu,helifu/kudu,InspurUSA/kudu,andrwng/kudu,cloudera/kudu,helifu/kudu,helifu/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,cloudera/kudu,helifu/kudu,cloudera/kudu,cloudera/kudu,EvilMcJerkface/kudu,cloudera/kudu,andrwng/kudu,EvilMcJerkface/kudu,andrwng/kudu,cloudera/kudu,helifu/kudu,EvilMcJerkface/kudu,helifu/kudu,cloudera/kudu,helifu/kudu,InspurUSA/kudu,InspurUSA/kudu,andrwng/kudu,andrwng/kudu,InspurUSA/kudu,cloudera/kudu,andrwng/kudu,InspurUSA/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,helifu/kudu,EvilMcJerkface/kudu,andrwng/kudu