emscripten, wayland, x11: Map SIZEALL to "all-scroll" instead of "move"

These previously mapped SIZEALL to "move", but "move" is not guaranteed
to be a four-pointed arrow: according to the CSS spec, it's actually
intended to be a drag-and-drop cursor, analogous to "alias" and "copy".
Map it to "all-scroll" instead, as in Wayland: while this is *also* not
semantically guaranteed to be a four-pointed arrow, it is at least
*suggested* to make it a four-pointed arrow.

Signed-off-by: Simon McVittie <smcv@collabora.com>
(cherry picked from commit aa6c390bbd)

src/video/emscripten/SDL_emscriptenmouse.c

@@ -172,7 +172,7 @@ static SDL_Cursor *Emscripten_CreateSystemCursor(SDL_SystemCursor id)
         cursor_name = "ns-resize";
         break;
     case SDL_SYSTEM_CURSOR_SIZEALL:
-        cursor_name = "move";
+        cursor_name = "all-scroll";
         break;
     case SDL_SYSTEM_CURSOR_NO:
         cursor_name = "not-allowed";