Need to use binary stdin and stdout on Windows

Before bug 505078 is fixed and subunit starts using a format resilient against newline mangling, subunit scripts need to change the mode of stdin and stdout to binary.

The short and hacky way to do this is something like:

import os, sys

...

if __name__ == "__main__":
    if sys.platform == "win32":
        import msvcrt
        for f in (sys.stdin, sys.stdout):
            msvcrt.setmode(f.fileno(), os.O_BINARY)
    main()