Fixed incorrect header guard macro definition
Fixed incorrect header guard macro definition

dpetrescu/zxing-cpp,yuanyuanxiang/zxing-cpp,yuanyuanxiang/zxing-cpp,blackberry/zxing-cpp,glassechidna/zxing-cpp,yumetodo/zxing-cpp,1yvT0s/zxing-cpp,1yvT0s/zxing-cpp,glassechidna/zxing-cpp,blackberry/zxing-cpp,TimZaman/zxing-cpp,yumetodo/zxing-cpp,TimZaman/zxing-cpp,dpetrescu/zxing-cpp