scorers: add missing explicit cast to suppress warnings
scorers: add missing explicit cast to suppress warnings

kenhys/groonga,groonga/groonga,kenhys/groonga,kenhys/groonga,groonga/groonga,groonga/groonga,groonga/groonga,groonga/groonga,groonga/groonga,kenhys/groonga,kenhys/groonga,kenhys/groonga,kenhys/groonga,kenhys/groonga,groonga/groonga,groonga/groonga