Floating Point overflow in FindBestSplit()

[stolk]

Describe the bug In the code, two values, both float max, are added, causing an overflow.

If floating point exceptions are enabled, the application will be terminated.

In the enc_ma.cc code:

196	      float lcost = std::numeric_limits<float>::max();
197	      float rcost = std::numeric_limits<float>::max();
198	      Predictor lpred = Predictor::Zero;
199	      Predictor rpred = Predictor::Zero;
200	      float Cost() const { return lcost + rcost; }

Calling Cost() can (and in practice will) add FLT_MAX to FLT_MAX.

Thread 1 "imageinout_test" received signal SIGFPE, Arithmetic exception.
0x00007ffff61c7291 in jxl::N_AVX2::FindBestSplit(jxl::TreeSamples&, float, std::vector<jxl::ModularMultiplierInfo, std::allocator<jxl::ModularMultiplierInfo> > const&, std::array<std::array<unsigned int, 2ul>, 2ul>, float, std::vector<jxl::PropertyDecisionNode, std::allocator<jxl::PropertyDecisionNode> >*)::SplitInfo::Cost() const
    (this=0x7fffffff8870) at /home/stolk/src/libjxl/lib/jxl/modular/encoding/enc_ma.cc:200