event/Chrono: add type alias TimePoint

src/event/Chrono.hxx

@@ -30,6 +30,7 @@ namespace Event {
 using Clock = std::chrono::steady_clock;
 
 using Duration = Clock::duration;
+using TimePoint = Clock::time_point;
 
 } // namespace Event
 

src/event/FineTimerEvent.hxx

@@ -64,7 +64,7 @@ class FineTimerEvent final
 	 * When is this timer due?  This is only valid if IsPending()
 	 * returns true.
 	 */
-	Event::Clock::time_point due;
+	Event::TimePoint due;
 
 public:
 	FineTimerEvent(EventLoop &_loop, Callback _callback) noexcept

src/event/TimerList.cxx

@@ -54,7 +54,7 @@ TimerList::Insert(FineTimerEvent &t) noexcept
 }
 
 Event::Duration
-TimerList::Run(const Event::Clock::time_point now) noexcept
+TimerList::Run(const Event::TimePoint now) noexcept
 {
 	while (true) {
 		auto i = timers.begin();

src/event/TimerList.hxx

@@ -71,5 +71,5 @@ public:
 	 * duration until the next timer expires.  Returns a negative
 	 * duration if there is no timeout.
 	 */
-	Event::Duration Run(Event::Clock::time_point now) noexcept;
+	Event::Duration Run(Event::TimePoint now) noexcept;
 };