the mode of fopen in example 'hw_decode' was wrong when used in windows

[elite_jwp]

In the example 'hw_decode.c:225', the code is as below:

 /* open the file to dump raw data */
 output_file = fopen(argv[3], "w+");

Here, the output file wasn't opened with mode "w+b" which would cause the data not be written "as is" in windows.

[mkver]

Duplicate of #8638.