BUG/MINOR: fix forcing fastinter in "on-error"

health_adjust() should requeue the task after changing its expire timer.

I noticed it on devel servers without load. We have long inter (10 seconds)
and short fasinter (100ms). But according to webserver logs, after a failed
request next check request was called with same 10s interval.

This patch should probably be backported to 1.4 which has the same feature.
diff --git a/src/checks.c b/src/checks.c
index 315ef7a..512eb2e 100644
--- a/src/checks.c
+++ b/src/checks.c
@@ -693,8 +693,11 @@
 
 	if (s->fastinter) {
 		expire = tick_add(now_ms, MS_TO_TICKS(s->fastinter));
-		if (s->check.task->expire > expire)
+		if (s->check.task->expire > expire) {
 			s->check.task->expire = expire;
+			/* requeue check task with new expire */
+			task_queue(s->check.task);
+		}
 	}
 }