Camera2: Filter out faces with 0 confidence.

        faces.setCapacity(metadata.number_of_faces);

        for (int i = 0; i < metadata.number_of_faces; i++) {

        size_t maxFaces = metadata.number_of_faces;

        for (size_t i = 0; i < maxFaces; i++) {

            if (faceScores[i] == 0) {

                metadata.number_of_faces--;

                continue;

            }

            camera_face_t face;

            face.rect[0] = l.mParameters.arrayXToNormalized(faceRects[i*4 + 0]);