[Libguestfs] [PATCH libnbd v3] Add Go language bindings (golang) (RHBZ#1814538).

This feature is roughly finished now, although it needs a few more tests and some examples. It's pretty much up to par with all the other bindings, but it lacks a completely safe AIO buffer. It won't stop you from freeing the buffer too early) because golang's GC inexplicably lacks a way to declare a root from C. I can probably do it with a global variable and ref counting on the golang side, but ... really? For ease of review I have placed the generated golang/src/libguestfs.org/libnbd directory here: http://oirase.annexia.org/tmp/libnbd-go/ Rich.