training: Fix compiler warnings (deprecated register keyword)
training: Fix compiler warnings (deprecated register keyword)

training/commontraining.cpp:824:3: warning:
 'register' storage class specifier is deprecated and incompatible with C++1z [-Wdeprecated-register]
...

Signed-off-by: Stefan Weil <8d4c780fcfdc41841e5070f4c43da8958ba6aec0@weilnetz.de>

jbarlow83/tesseract,UB-Mannheim/tesseract,stweil/tesseract,jbarlow83/tesseract,jbarlow83/tesseract,UB-Mannheim/tesseract,stweil/tesseract,amitdo/tesseract,jbarlow83/tesseract,UB-Mannheim/tesseract,stweil/tesseract,stweil/tesseract,tesseract-ocr/tesseract,tesseract-ocr/tesseract,stweil/tesseract,amitdo/tesseract,tesseract-ocr/tesseract,amitdo/tesseract,tesseract-ocr/tesseract,jbarlow83/tesseract,amitdo/tesseract,UB-Mannheim/tesseract,amitdo/tesseract,UB-Mannheim/tesseract,tesseract-ocr/tesseract