Multiple hackrf boards support (patch)

Hi, I have a little pull request for gr-osmosdr, to enable multiple devices support for hackrf. This allows doing things like full duplex using two boards in a single graph. You can specify either hackrf=0 and hackrf=1 to select by a device index, or the serial number (or an unique suffix of a serial number), hackrf=f00d and hackrf=1234abba. hackrf_info lists multiple devices and their serial numbers. Apps like gqrx seem to magically work, too, and allow device selection. The hackrf project just merged the pull request for libhackrf & tools 3 days ago, and it's already available in macports at least. The gr-osmosdr patches here do work against old libhackrf as before, it detects the presence of the new hackrf_device_list API and enables multiple device support only if it is available. What is the preferred patch format, I have the changes available as a feature branch in github? https://github.com/hessu/gr-osmosdr/tree/feature/hackrf_multidev - Hessu