multi: add global log for wallet db postgres back

kvdb/postgres/config.go

@@ -9,4 +9,5 @@ type Config struct {
 	Dsn            string        `long:"dsn" description:"Database connection string."`
 	Timeout        time.Duration `long:"timeout" description:"Database connection timeout. Set to zero to disable."`
 	MaxConnections int           `long:"maxconnections" description:"The maximum number of open connections to the database. Set to zero for unlimited."`
+	WithGlobalLock bool          `long:"withgloballock" description:"Use a global lock to ensure a single writer."`
 }