Use HEAPU8.set rather than Module.HEAPU8.set (thanks @sbc100!)

The Module object is the external interface to the application, internal symbols like HEAPU8 don't need to be exported to be used and usage should not be prefixed with Module.

Fixes https://github.com/libsdl-org/SDL/issues/13156
Closes https://github.com/libsdl-org/SDL/pull/13157

(cherry picked from commit cf6c42e6e6cca075b196a8ee69e96a0d8ba0652b)

src/camera/emscripten/SDL_camera_emscripten.c

@@ -61,7 +61,7 @@ static SDL_CameraFrameResult EMSCRIPTENCAMERA_AcquireFrame(SDL_Camera *device, S
 
         SDL3.camera.ctx2d.drawImage(SDL3.camera.video, 0, 0, w, h);
         const imgrgba = SDL3.camera.ctx2d.getImageData(0, 0, w, h).data;
-        Module.HEAPU8.set(imgrgba, rgba);
+        HEAPU8.set(imgrgba, rgba);
 
         return 1;
     }, device->actual_spec.width, device->actual_spec.height, rgba);