remove lines that restore window on close (#774)

src/graphic/Fast3D/gfx_dxgi.cpp

@@ -302,7 +302,6 @@ void GetMonitorHzPeriod(std::tuple<HMONITOR, RECT, BOOL> Monitor, double& Freque
 }
 
 static void gfx_dxgi_close() {
-    ShowWindow(dxgi.h_wnd, SW_NORMAL); // Restore window before closing, so normal window pos and size is saved
     dxgi.is_running = false;
 }
 

src/graphic/Fast3D/gfx_sdl2.cpp

@@ -285,7 +285,6 @@ static int target_fps = 60;
 #define FRAME_INTERVAL_US_DENOMINATOR (target_fps)
 
 static void gfx_sdl_close(void) {
-    SDL_RestoreWindow(wnd); // Restore window before closing, so normal window pos and size is saved
     is_running = false;
 }