No POLLIN fd on Linux, no POLLOUT on Darwin

[hadess]

As discovered by Hendrik:
​http://thread.gmane.org/gmane.network.protocols.obex.openobex.user/1582/focus=1586

There's no POLLIN fd on Linux, or POLLOUT fds, on Darwin

[dsd]

And why is that a problem?

The application shouldn't make any assumptions about the fd set that comes back. It should just do what libusb suggests, polling all the fd's (not looking for specific ones) in the directions suggested by libusb. The fd set will also change from release to release, as it has been doing recently. Perhaps we can improve the documentation in this area.

[dsd]

updated the documentation. If this application is somehow bothered by the events which it has to monitor, or is selectively polling only certain descriptors from the set then it is likely to run into problems down the line.