hhvm: fixed warning when seeking to unknown index
hhvm: fixed warning when seeking to unknown index

nextras/dbal,Mikulas/dbal,dyamon-cz/nextras-dbal,dyamon-cz/nextras-dbal,nextras/dbal,dyamon-cz/nextras-dbal,jasir/dbal,nextras/dbal,jasir/dbal,Mikulas/dbal,jasir/dbal,Mikulas/dbal