MB-11145: corrected tag for gperftools

Change-Id: I192871bfca0d4e7dd7f37bab64b0b917658d1d6f
Reviewed-on: http://review.couchbase.org/37636
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Chris Hillery <ceej@couchbase.com>