Stream class hangs while trying to print some floating point values

[AlexeySachkov]

The following code hangs even on HOST device:

#include <CL/sycl.hpp>                                                    
                                                                          
#include <iostream>                                                       
#include <cstring>                                                        
#include <vector>                                                         
                                                                          
int main() {                                                              
  cl::sycl::queue Q;                                                      
  float FData = -1;                                                       
  std::cout << "FData: " << FData << std::endl;                           
  cl::sycl::buffer<float> Buf(&FData, cl::sycl::range<1>(1));             
                                                                          
  Q.submit([&](cl::sycl::handler &CGH) {                                  
    cl::sycl::stream S(1024, 100, CGH);                                   
    auto Acc = Buf.template get_access<cl::sycl::access::mode::read>(CGH);
    CGH.single_task<class K>([=]() {                                      
      float F = Acc[0];                                                   
      S << "F / 0 = " << (F / 0.0) << cl::sycl::endl;    
    });                                                                   
  });                                                                     
  Q.wait();                                                               
                                                                          
  return 0;                                                               
}                                                                         

If I understand correctly, F / 0.0 produces NaN and everything hangs somewhere around https://github.com/intel/llvm/blob/sycl/sycl/include/CL/sycl/detail/stream_impl.hpp#L164

[againull]

Fix is merged #522