daemon/http: improve handling of stream errors

daemon/http: improve handling of stream errors

The on_frame_recv() callback ins't guaranteed to be called by nghttp2.
This can happen e.g. in a case when nghttp2 issues a PROTOCOL_ERROR
RST_STREAM frame. Previously, it would leave the connection in a
stream-processing state, making it completely useless.

While this guarantees a cleanup will be called eventually, some streams
may still get ignored due to the order of various callbacks and data
processing procedures. Still, it's better than the previous
implementation.