message: gltfio: fix AABB when instancing is enabled
  If a client opts in to AABB computation and uses instancing, the AABB
  would be clobbered with an infinite box.
  Fixes
diff: @@ -967,6 +967,7 @@ void ResourceLoader::updateBoundingBoxes(FFilamentAsset* asset) const {
  SYSTRACE_CALL();
  auto& rm = pImpl->mEngine->getRenderableManager();
  auto& tm = pImpl->mEngine->getTransformManager();
  + NodeMap& nodeMap = asset->mInstances.empty() ? asset->mNodeMap : asset->mInstances[0]->nodeMap;
  // The purpose of the root node is to give the client a place for custom transforms.
  // Since it is not part of the source model, it should be ignored when computing the
  @@ -1000,7 +1001,7 @@ void ResourceLoader::updateBoundingBoxes(FFilamentAsset* asset) const {
  // Collect all mesh primitives that we wish to find bounds for.
  std::vector<cgltf_primitive const*> prims;
  - for (auto iter : asset->mNodeMap) {
  + for (auto iter : nodeMap) {
  const cgltf_mesh* mesh = iter.first->mesh;
  if (mesh) {
  for (cgltf_size index = 0, nprims = mesh->primitives_count; index < nprims; ++index) {
  @@ -1025,7 +1026,7 @@ void ResourceLoader::updateBoundingBoxes(FFilamentAsset* asset) const {
  // Compute the asset-level bounding box.
  size_t primIndex = 0;
  Aabb assetBounds;
  - for (auto iter : asset->mNodeMap) {
  + for (auto iter : nodeMap) {
  const cgltf_mesh* mesh = iter.first->mesh;
  if (mesh) {
  // Find the object-space bounds for the renderable by unioning the bounds of each prim.
  