Switch system_clock to high_resolution_clock, work around win32 sleep_for/sleep_until bug when clocks go backwards

src/recomp/cont.cpp

@@ -3,10 +3,10 @@
 
 static ultramodern::input_callbacks_t input_callbacks;
 
-std::chrono::system_clock::time_point input_poll_time;
+std::chrono::high_resolution_clock::time_point input_poll_time;
 
 void update_poll_time() {
-    input_poll_time = std::chrono::system_clock::now();
+    input_poll_time = std::chrono::high_resolution_clock::now();
 }
 
 extern "C" void recomp_set_current_frame_poll_id(uint8_t* rdram, recomp_context* ctx) {
@@ -18,7 +18,7 @@ extern "C" void recomp_measure_latency(uint8_t* rdram, recomp_context* ctx) {
 }
 
 void ultramodern::measure_input_latency() {
-    // printf("Delta: %ld micros\n", std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::system_clock::now() - input_poll_time));    
+    // printf("Delta: %ld micros\n", std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::high_resolution_clock::now() - input_poll_time));    
 }
 
 void set_input_callbacks(const ultramodern::input_callbacks_t& callbacks) {

src/recomp/recomp.cpp

@@ -429,8 +429,7 @@ void recomp::start(ultramodern::WindowHandle window_handle, const ultramodern::a
     }, window_handle, rdram_buffer.get()};
 
     while (!exited) {
-        using namespace std::chrono_literals;
-        std::this_thread::sleep_for(1ms);
+        ultramodern::sleep_milliseconds(1);
         if (gfx_callbacks.update_gfx != nullptr) {
             gfx_callbacks.update_gfx(gfx_data);
         }

src/ui/ui_config.cpp

@@ -322,10 +322,7 @@ public:
 			throw std::runtime_error("Failed to make RmlUi data model for the graphics config menu");
 		}
 
-		{
-			using namespace std::chrono_literals;
-			std::this_thread::sleep_for(50ms);
-		}
+		ultramodern::sleep_milliseconds(50);
 		new_options = ultramodern::get_graphics_config();
 		bind_config_list_events(constructor);