Vulkan: Avoid crash on double DeviceLost.

This caused Android to crash when switching to OpenGL, because the
destructor would try to deinit again.  There weren't any objects, but
draw_ was no longer valid.

UI/NativeApp.cpp

@@ -1048,13 +1048,13 @@ bool CreateGlobalPipelines() {
 }
 
 void NativeShutdownGraphics() {
+	INFO_LOG(SYSTEM, "NativeShutdownGraphics");
+
 	screenManager->deviceLost();
 
 	if (gpu)
 		gpu->DeviceLost();
 
-	INFO_LOG(SYSTEM, "NativeShutdownGraphics");
-
 #if PPSSPP_PLATFORM(WINDOWS)
 	delete winAudioBackend;
 	winAudioBackend = nullptr;