RFR: 8365782: Remove unnecessary inclusion of <stdlib.h> in jfrOSInterface.cpp

[Albert Mingkun Yang]

On Sun, 5 Oct 2025 17:34:16 GMT, jonghoonpark <duke at openjdk.org> wrote:

> related jira issue: https://bugs.openjdk.org/browse/JDK-8365782
> 
> ---
> 
> ### Changes
> 
> As described in the issue, I have removed the unnecessary inclusion of `stdlib.h`.
> 
> This was first discussed in [this comment](https://github.com/openjdk/jdk/pull/26800#discussion_r2278998210).
> 
> As noted in the discussion, `generate_environment_variables_events` also appears to be unimplemented, so it has been removed as well.
> 
> ---
> 
> ### Verification
> 
> - Checked that no functions from `stdlib.h` are called in the file.
> - Checked that the `generate_environment_variables_events` function is not implemented anywhere in the codebase.
> - Ran the `tier1` tests after the changes and confirmed that there were no issues.
> 
> Please let me know if there are any additional or more appropriate verification steps I should perform.

Marked as reviewed by ayang (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/27639#pullrequestreview-3303800195