Method locate

src/jrd/recsrc/WindowedStream.cpp:73–78

		void nullRecords(thread_db* tdbb) const override;

		void locate(thread_db* tdbb, FB_UINT64 position) const override
		{
			Request* const request = tdbb->getRequest();
			Impure* const impure = request->getImpure<Impure>(m_impure);
			impure->irsb_position = position;
		}

		FB_UINT64 getCount(thread_db* tdbb) const override
		{