Add ninja build files to .gitignore
Add ninja build files to .gitignore

Change-Id: Ifd406bb22e09910832e29a330d83dd404d5b5031
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/6719
Reviewed-by: Todd Lipcon <2c763d726a8c2f6afda9be7e0e56a2caa6bb5e6b@cloudera.com>
Tested-by: jenkins

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