Fix hash implementation for SerializedBlockCache

src/server.h

@@ -425,11 +425,10 @@ private:
 		std::unordered_set<session_t> waiting_players;
 	};
 
-	// the standard library does not implement std::hash for pairs so we have this:
+	// The standard library does not implement std::hash for pairs so we have this:
 	struct SBCHash {
 		size_t operator() (const std::pair<v3s16, u16> &p) const {
-			return (((size_t) p.first.X) << 48) | (((size_t) p.first.Y) << 32) |
-				(((size_t) p.first.Z) << 16) | ((size_t) p.second);
+			return std::hash<v3s16>()(p.first) ^ p.second;
 		}
 	};