Method swap

src/fl/stl/shared_ptr.h:309–312

    }

    void swap(shared_ptr& other) FL_NOEXCEPT {
        fl::swap(mPtr, other.mPtr);
        fl::swap(mControlBlock, other.mControlBlock);
    }

    void swap(shared_ptr&& other) FL_NOEXCEPT {
        fl::swap(mPtr, other.mPtr);