Replacing the tick count timer with xplat abstraction (also better rate).

Fixes #346.

src/xenia/base/clock_win.cc

@@ -36,6 +36,8 @@ uint64_t Clock::QueryHostSystemTime() {
   return (uint64_t(t.dwHighDateTime) << 32) | t.dwLowDateTime;
 }
 
-uint32_t Clock::QueryHostUptimeMillis() { return ::GetTickCount(); }
+uint32_t Clock::QueryHostUptimeMillis() {
+  return uint32_t(QueryHostTickCount() / (host_tick_frequency() / 1000));
+}
 
 }  // namespace xe