RFR: 8256178: Add RAII object for file lock [v2]

[Thomas Stuefe]

On Wed, 11 Nov 2020 07:25:12 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

>> This PR is subtask of [JDK-8256008](https://bugs.openjdk.java.net/browse/JDK-8256008) (#1106)
>> 
>> `LogFileStreamOutput::write()` uses `os::flockfile()` and `os::funlockfile()` to serialize write ops. It is better to use RAII because we can ensure `os::funlockfile()` call.
>
> Yasumasa Suenaga has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove funlockfile() call

Missed that one, sorry. Looks good (But I see you already pushed).

..Thomas

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PR: https://git.openjdk.java.net/jdk/pull/1156