Missing cast from reference to pointer

OS X/clang build failed with 

Logger.cpp:169:8: error: cannot cast from type 'std::ostream' (aka 'basic_ostream<char>') to pointer type 'void *'
                        if ((void*)stream == (void*)output._stream)
                            ^~~~~~~~~~~~~
Logger.cpp:169:25: error: cannot cast from type 'std::ostream' (aka 'basic_ostream<char>') to pointer type 'void *'
                        if ((void*)stream == (void*)output._stream)
                                             ^~~~~~~~~~~~~~~~~~~~~

because stream and LoggerOutput._stream are references. Need an & operator before casting