Lighttpd

As I tried finding out when to decrement load, I found the following
line:

COUNTER_DEC(sess->proxy_backend->load);

in proxy_remove_backend_connection(...) and proxy_recycle_backend_connection(...).

Both only check for sess / sess->proxy_con and then decrement in every
case; but proxy_recycle_backend_connection calls
proxy_remove_backend_connection if it does not keep-alive, so in this
case load gets decremented twice.
Both set sess->proxy to NULL, so it does not happen again.

COUNTER_DEC decrements only if it not 0, so nothing seriously bad
happens.

Proposed change: Execute COUNTER_DEC in recycle only when remove gets not called (see patch).