Avoid error when there is no section for buffer pool info.
Avoid error when there is no section for buffer pool info.

This is probably because innodb_buffer_pool_instances is 1 by default meaning
you don't get the 'INDIVIDUAL BUFFER POOL INFO' section.

art-spilgames/mysql-statsd,bnkr/mysql-statsd,db-art/mysql-statsd,spilgames/mysql-statsd