cmd/lncli: use bitsize of 64 to read output index

In the lnrpc proto, we use either int64 or uint32 for output index. So
to keep things consistent, we should use a bitsize of 64 when reading an
output index from a string. Otherwise, we fail could fail to parse an
index that is valid based on the types we define in the protos.

cmd/lncli/commands.go

@@ -2052,7 +2052,7 @@ func parseChanPoint(s string) (*lnrpc.ChannelPoint, error) {
 		return nil, errBadChanPoint
 	}
 
-	index, err := strconv.ParseInt(split[1], 10, 32)
+	index, err := strconv.ParseInt(split[1], 10, 64)
 	if err != nil {
 		return nil, fmt.Errorf("unable to decode output index: %v", err)
 	}