Always show the battery percentage unless it is unknown

static void draw_percent(const animation& anim)

{

    if (anim.cur_level <= 0 || anim.cur_status != BATTERY_STATUS_CHARGING) return;

    int cur_level = anim.cur_level;

    if (anim.cur_status == BATTERY_STATUS_FULL) {

        cur_level = 100;

    }

    if (cur_level <= 0) return;

    const animation::text_field& field = anim.text_percent;

    if (field.font == nullptr || field.font->char_width == 0 || field.font->char_height == 0) {

        return;

    }

    std::string str = base::StringPrintf("%d%%", anim.cur_level);

    std::string str = base::StringPrintf("%d%%", cur_level);

    int x, y;

    determine_xy(field, str.size(), &x, &y);