修复#4339：SQLUpdateStatement缺少对with语句的访问支持

src/main/java/com/alibaba/druid/sql/ast/statement/SQLUpdateStatement.java

@@ -170,6 +170,10 @@ public class SQLUpdateStatement extends SQLStatementImpl implements SQLReplaceab
 
     protected void acceptChild(SQLASTVisitor visitor)
     {
+        if (with != null) {
+            with.accept(visitor);
+        }
+
         if (tableSource != null) {
             tableSource.accept(visitor);
         }