Fix warning for Android NDK compiler: "function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]"

https://stackoverflow.com/questions/42125/warning-error-function-declaration-isnt-a-prototype
In C int foo() and int foo(void) are different functions. int foo() accepts an arbitrary number of arguments, while int foo(void) accepts 0 arguments. In C++ they mean the same thing.

src/render/ps2/SDL_render_ps2.c

@@ -55,7 +55,7 @@ typedef struct
 static int vsync_sema_id = 0;
 
 /* PRIVATE METHODS */
-static int vsync_handler()
+static int vsync_handler(void)
 {
     iSignalSema(vsync_sema_id);