BigInteger::Divide: fix a bug in (unused) corner case
BigInteger::Divide: fix a bug in (unused) corner case

q and r might be temporary local variables in that case and not point
to qq and rr.

nu-book/zxing-cpp,huycn/zxing-cpp,huycn/zxing-cpp,huycn/zxing-cpp,huycn/zxing-cpp,huycn/zxing-cpp,huycn/zxing-cpp,huycn/zxing-cpp,nu-book/zxing-cpp,nu-book/zxing-cpp,nu-book/zxing-cpp,nu-book/zxing-cpp,nu-book/zxing-cpp,huycn/zxing-cpp,nu-book/zxing-cpp,nu-book/zxing-cpp