main: allow node to start without bdk wallet

Since bdkwallet is enabled by default, if utreexod wasn't built with
bdkwallet, it will not start. This change allows the node to start
without the bdkwallet.

Author: kcalvinalvin

server.go

@@ -3556,7 +3556,14 @@ func newServer(listenAddrs, agentBlacklist, agentWhitelist []string,
 			DataDir:     cfg.DataDir,
 		})
 		if err != nil {
-			return nil, err
+			if err == bdkwallet.ErrNoBDK {
+				s.bdkWallet = nil
+				cfg.NoBdkWallet = true
+				btcdLog.Infof("Unable to enable bkdwallet as utreexod wasn't built with bdkwallet. " +
+					"Starting node without bdkwallet.")
+			} else {
+				return nil, err
+			}
 		}
 	}