cmake: do not try to even configure training tools if pkg-config is not present.
cmake: do not try to even configure training tools if pkg-config is not present.

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