[macos] add .DS_Store entry into .gitignore
[macos] add .DS_Store entry into .gitignore

Change-Id: I60e4831d4fb58c8e94a7748b799ba98cda13ba5d
Reviewed-on: http://gerrit.cloudera.org:8080/14226
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>
Tested-by: Kudu Jenkins

helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu