SFI: add and use AsyncBlockingQueue from Rapicorn
SFI: add and use AsyncBlockingQueue from Rapicorn

Import is based on Rapicorn commit id:
	bf228016cba3f6d252ee2cc38e1ed32607f37bf0

Signed-off-by: Tim Janik <6ec6ff229c4e1c5bbd5933ee92e6c5832ff023bb@gnu.org>

GNOME/beast,tim-janik/beast,swesterfeld/beast,swesterfeld/beast,swesterfeld/beast,GNOME/beast,GNOME/beast,tim-janik/beast,swesterfeld/beast,tim-janik/beast,tim-janik/beast,GNOME/beast,swesterfeld/beast,tim-janik/beast,tim-janik/beast,swesterfeld/beast,GNOME/beast,swesterfeld/beast,GNOME/beast,tim-janik/beast,GNOME/beast