Fix compiler warning from other peoples code.
Fix compiler warning from other peoples code.

andre-senna/opencog,AmeBel/opencog,andre-senna/opencog,AmeBel/opencog,AmeBel/opencog,andre-senna/opencog,AmeBel/opencog,andre-senna/opencog,AmeBel/opencog,andre-senna/opencog,AmeBel/opencog,andre-senna/opencog,AmeBel/opencog,andre-senna/opencog