BUG/MAJOR: http: compression still has defects on chunked responses

The compression state machine happens to start work it cannot undo if
there's no more data in the input buffer, and has trouble accounting
for it. Fixing it requires more than a few lines, as the confusion is
in part caused by the way the pointers to the various places in the
message are handled internally. So as a temporary fix, let's disable
compression on chunk-encoded responses. This will give us more time
to perform the required changes.