replace SDL_HINT_ANDROID_SEPARATE_MOUSE_AND_TOUCH with
SDL_HINT_MOUSE_TOUCH_EVENTS and SDL_HINT_TOUCH_MOUSE_EVENTS per sdl2
2.0.10 update instructions.

Index: src/input.cpp
--- src/input.cpp.orig
+++ src/input.cpp
@@ -91,7 +91,8 @@ void input_init(void)
 
   // TODO: don't attempt to simulate mouse events from touch events -
   // fake mouse events often are de-centered
-  SDL_SetHint(SDL_HINT_ANDROID_SEPARATE_MOUSE_AND_TOUCH, "0");
+  SDL_SetHint(SDL_HINT_MOUSE_TOUCH_EVENTS, "1");
+  SDL_SetHint(SDL_HINT_TOUCH_MOUSE_EVENTS, "1");
 
   /* Touch devices */
   {
