BUG/MINOR: mux-h1: Don't set CS_FL_EOI too early for protocol upgrade requests

BUG/MINOR: mux-h1: Don't set CS_FL_EOI too early for protocol upgrade requests

When a protocol upgrade request is received, once parsed, it is waiting for
the response in the DONE state. But we must not set the flag CS_FL_EOI
because we don't know if a protocol upgrade will be performed or not.

Now, it is set on the response path, if both sides reached the DONE
state. If a protocol upgrade is finally performed, both side are switched in
TUNNEL state. Thus the CS_FL_EOI flag is not set.

If backported, this patch must be adapted because for now it relies on last
2.4-dev changes. It may be backported as far as 2.0.