android 新增api，编译current.txt异常问题

在新增api后，进行系统编译前，需要先在系统中使用make命令，对current.txt进行自动更新。

(1) android 低版本，新增api直接编译，会出现入下异常：

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You have tried to change the API from what has been previously approved.

To make these errors go away, you have two choices:

1) You can add "@hide" javadoc comments to the methods, etc. listed in the

errors above.

2) You can update current.txt by executing the following command:

make update-api

To submit the revised current.txt to the main Android repository,

you will need approval.

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需要配置编译环境后，执行 make update-ap 系统自动更新current文档，再进行编译。

(2) anndroid 高版本，新增api直接编译，会出现如下异常：

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You have tried to change the API from what has been previously approved.

To make these errors go away, you have two choices:
   1. You can add '@hide' javadoc comments to the methods, etc. listed in the
      errors above.

   2. You can update current.txt by executing the following command:
         make api-stubs-docs-update-current-api

      To submit the revised current.txt to the main Android repository,
      you will need approval.
******************************

 需要配置编译环境后，执行 make api-stubs-docs-update-current-api 系统自动更新current文档，再进行编译。

最后，保存或上传current.txt文件更新即可。