[SfStats] Add event connection count to atom proto.

    // Total time that was spent performing animations.

    // This is derived from the present-to-present layer histogram

    optional int64 animation_millis = 5;

    // Total number of event connections tracked by SurfaceFlinger at the time

    // of this pull. If this number grows prohibitively large, then this can

    // cause jank due to resource contention.

    optional int32 event_connection_count = 6;

}

/**