When going on a waitinglist, the HTTP1 step counter was set to
S_STP_H1BUSY to allow conditions to be checked on return specific to
having been on a waitinglist. Though the step counter was set after
entering the waitinglist, and if the session was rescheduled
immediately on another thread a race opened which would mess up the
state handling.

Fix this by elliminating the S_STP_H1BUSY step, and having condition
checks on req->hash_objhead in the S_STP_H1PROC state to handle the
waitinglist return specific checks.

The panic output has been changed to include the req->hash_objhead
pointer if set. This exposes the waitinglist condition in the panic
output which would otherwise be hidden by the removal of the
S_STP_H1BUSY step.

Fixes: #2117