BUG/MEDIUM: sessions: Don't use t->state.

In session_expire_embryonic(), don't use t->state, use the "state" argument
instead, as t->state has been cleaned before we're being called.
diff --git a/src/session.c b/src/session.c
index 1d66b73..d7d8544 100644
--- a/src/session.c
+++ b/src/session.c
@@ -388,7 +388,7 @@
 {
 	struct session *sess = context;
 
-	if (!(t->state & TASK_WOKEN_TIMER))
+	if (!(state & TASK_WOKEN_TIMER))
 		return t;
 
 	session_kill_embryonic(sess);