BUG/MINOR: http-ana: increment internal_errors counter on response error

A bug was introduced in the commit cff0f739e51 ("MINOR: counters: Review
conditions to increment counters from analysers"). The internal_errors
counter for the target server was incremented twice. The counter for the
session listener needs to be incremented instead.

This must be backported everywhere the commit cff0f739e51 is.
diff --git a/src/http_ana.c b/src/http_ana.c
index 7d9abdb..0e3d060 100644
--- a/src/http_ana.c
+++ b/src/http_ana.c
@@ -2009,8 +2009,8 @@
 		s->flags |= SF_ERR_INTERNAL;
 	_HA_ATOMIC_INC(&sess->fe->fe_counters.internal_errors);
 	_HA_ATOMIC_INC(&s->be->be_counters.internal_errors);
-	if (objt_server(s->target))
-		_HA_ATOMIC_INC(&__objt_server(s->target)->counters.internal_errors);
+	if (sess->listener && sess->listener->counters)
+		_HA_ATOMIC_INC(&sess->listener->counters->internal_errors);
 	if (objt_server(s->target))
 		_HA_ATOMIC_INC(&__objt_server(s->target)->counters.internal_errors);
 	goto return_prx_err;