The 'black_hole' component provides dummy implementations of common
session interfaces.

At this time, the following sessions are provided if enabled
in the configuration of the component.

* Audio_in
* Audio_out
* Capture
* Event
* Nic
* Uplink
* ROM
* Gpu
* Usb
* Play
* Record
* Log
* Terminal

HID-configuration snippet:

+ config
  + audio_in
  + audio_out
  + capture
  + event
  + nic
  + uplink
  + rom
  + gpu
  + usb
  + play
  + record
  + log
  + terminal
-

Black hole optionally requests the following sessions as client.

* Uplink client

+ config
  + uplink_client
-
