Accepts &self for Cursor::key() and ::value() (#3448)
Accepts &self for Cursor::key() and ::value() (#3448)

Signed-off-by: Breezewish <a3a422de9ee6740e0686b745435c2f95bb3fed6b@pingcap.com>

c4pt0r/tikv,pingcap/tikv,pingcap/tikv,BusyJay/tikv,BusyJay/tikv,BusyJay/tikv,BusyJay/tikv