BUG/MEDIUM: stream: don't ignore res.analyse_exp anymore

It happens that no single analyser has ever needed to set res.analyse_exp,
so that process_stream() didn't consider it when computing the next task
expiration date. Since Lua actions were introduced in 1.6, this can be
needed on http-response actions for example, so let's ensure it's properly
handled.

Thanks to Nick Dimov for reporting this bug. The fix needs to be
backported to 1.7 and 1.6.
diff --git a/src/stream.c b/src/stream.c
index 48c4ba5..19d94f3 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -2427,6 +2427,8 @@
 
 		t->expire = tick_first(t->expire, req->analyse_exp);
 
+		t->expire = tick_first(t->expire, res->analyse_exp);
+
 		if (si_f->exp)
 			t->expire = tick_first(t->expire, si_f->exp);