Fix division by zero during CJK training.
Fix division by zero during CJK training.

UB-Mannheim/tesseract,tesseract-ocr/tesseract,amitdo/tesseract,tesseract-ocr/tesseract,tesseract-ocr/tesseract,stweil/tesseract,stweil/tesseract,tesseract-ocr/tesseract,UB-Mannheim/tesseract,stweil/tesseract,amitdo/tesseract,UB-Mannheim/tesseract,UB-Mannheim/tesseract,stweil/tesseract,tesseract-ocr/tesseract,amitdo/tesseract,amitdo/tesseract,stweil/tesseract,amitdo/tesseract,UB-Mannheim/tesseract