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 #13156
Closes #13157

(cherry picked from commit cf6c42e)

Author: slouken

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);