add SDL_AndroidShowToast for https://developer.android.com/reference/android/widget/Toast

include/SDL_system.h

@@ -215,6 +215,22 @@ extern DECLSPEC const char * SDLCALL SDL_AndroidGetExternalStoragePath(void);
  */
 extern DECLSPEC SDL_bool SDLCALL SDL_AndroidRequestPermission(const char *permission);
 
+/**
+   \brief Show android toast notification
+
+    Show toast in UI thread [https://developer.android.com/guide/topics/ui/notifiers/toasts]
+    Params description
+    message   : text message to be shown
+    duration  : 0 - short [https://developer.android.com/reference/android/widget/Toast#LENGTH_SHORT],
+                1 - long  [https://developer.android.com/reference/android/widget/Toast#LENGTH_LONG]
+    gravity   : the location at which the notification should appear on the screen.
+                It's an optional parameter. Set -1 if you don't want specify any gravity or
+                choose some value from https://developer.android.com/reference/android/view/Gravity
+    xOffset   : set this parameter only when gravity >=0
+    yOffset   : set this parameter only when gravity >=0
+*/
+extern DECLSPEC int SDLCALL SDL_AndroidShowToast(const char* message, int duration, int gravity, int xOffset, int yOffset);
+
 #endif /* __ANDROID__ */
 
 /* Platform specific functions for WinRT */