Style: Fixup instances of void arguments

The style we have here is that functions with no arguments are to have
explicit `void` arguments, even though this doesn't apply in C++,
because it does apply in C.

Unfortunately, some have slipped through the cracks. This commit fixes
them.

desktop_version/src/Render.cpp

@@ -2284,7 +2284,7 @@ static void draw_roomname_menu(void)
  * the same in Flip Mode. */
 #define FLIP(y, h) (graphics.flipmode ? 220 - (y) - (h) : (y))
 
-static MapRenderData getmaprenderdata()
+static MapRenderData getmaprenderdata(void)
 {
     MapRenderData data;