protocol.read_inet and protocol.write_inet fail on Windows

As mentioned in PYTHON-20, Python's socket module does not implement inet_pton or inet_ntop. These functions are used in protocol.py, specifically read_inet and write_inet. I've observed the failure myself in a Windows 7 environment, but I think it should fail for any Windows environment, except maybe Cygwin.

The fix for this may be similar to the fix for PYTHON-18.