setup.py: Adjustments to make setup.py run in py3k. In py3k, subprocess.Popen.communicate's output are bytes objects. String literals are Unicode objects. Thus, when a bytes object startswith method is called, with string literals, it fails. What this patch does is: * Convert the string (unicode in py3k) literals to bytes objects; * As "bytes" is not a builtin in python < 2.6, it defines a "b" helper function that merely returns its argument, as suggested by Antoine Pitrou.