refactor parseSelectList

sharding-jdbc-core/src/main/java/com/dangdang/ddframe/rdb/sharding/parsing/parser/statement/dql/select/AbstractSelectParser.java

@@ -123,7 +123,7 @@ public abstract class AbstractSelectParser implements SQLStatementParser {
     protected void parseBeforeSelectList() {
     }
     
-    protected final void parseSelectList() {
+    private void parseSelectList() {
         do {
             parseSelectItem();
         } while (sqlParser.skipIfEqual(Symbol.COMMA));