squash reallocs in command buffers by using large prealloced buffer, directly use virtual memory with it so os allocs on demand

mark raw clock functions as noinline, the way msvc was inlining them and ordering the branches meant that rdtsc would often be speculatively executed
add alternative clock impl for win, instead of using queryperformancecounter we grab systemtime from kusershared. it does not have the same precision as queryperformancecounter, we only have 100 nanosecond precision, but we round to milliseconds so it never made sense to use the performance counter in the first place
stubbed out the "guest clock mutex"... (the entirety of clock.cc needs a rewrite)
added some helpers for minf/maxf without the nan handling behavior

src/xenia/base/threading_timer_queue.cc

@@ -205,7 +205,7 @@ void TimerQueueWaitItem::Disarm() {
     spinner.spin_once();
   }
 }
-
+//unused
 std::weak_ptr<WaitItem> QueueTimerOnce(std::function<void(void*)> callback,
                                        void* userdata,
                                        WaitItem::clock::time_point due) {
@@ -213,7 +213,7 @@ std::weak_ptr<WaitItem> QueueTimerOnce(std::function<void(void*)> callback,
       std::make_shared<WaitItem>(std::move(callback), userdata, &timer_queue_,
                                  due, WaitItem::clock::duration::zero()));
 }
-
+// only used by HighResolutionTimer
 std::weak_ptr<WaitItem> QueueTimerRecurring(
     std::function<void(void*)> callback, void* userdata,
     WaitItem::clock::time_point due, WaitItem::clock::duration interval) {