make update-api

1)  添加系统API或者修改@hide的API后，需要执行

     make update-api，然后再make

2) 修改公共api后，需要

     make update-api

     比较framework/base/api 下的current.xml跟原始x.xml(比如2.2为8.xml, 2.3.3为10.xml)，同时修改x.xml

     然后make

see build/core/apicheck_msg_current.txt

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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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