8337416: Fix -Wzero-as-null-pointer-constant warnings in misc. runtime code

[kimbarrett]

Please review this (perhaps trivial?) change that removes some uses of literal
0 as a null pointer constant in misc. runtime code. Most are changed to use
nullptr.

Testing: mach5 tier1

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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• Commit message must refer to an issue

Issue

• JDK-8337416: Fix -Wzero-as-null-pointer-constant warnings in misc. runtime code (Enhancement - P4)

Reviewers

• David Holmes (@dholmes-ora - Reviewer)
• Julian Waters (@TheShermanTanker - Committer)

Reviewing

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8337416: Fix -Wzero-as-null-pointer-constant warnings in misc. runtime code

Reviewed-by: dholmes, jwaters

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[mlbridge]

Webrevs

• 00: Full (ae592c18)

[dholmes-ora]

This looks fine, and I think trivial.

I think there is an existing bug but probably better to file a separate JBS issue for that.

Thanks

[dholmes-ora]

This looks like a bug. I think someone used 0 aka fd0 when they needed stdout for fflush.

[kimbarrett]

I assumed there was some reason for flushing all here, but you are right, this is probably a bug.

[TheShermanTanker]

Looks Good!

[kimbarrett]

Thanks for reviews @dholmes-ora and @TheShermanTanker .

I'll file a followup bug for the pre-existing fflush argument that @dholmes-ora pointed out.

[kimbarrett]

/integrate

[openjdk]

Going to push as commit bc7c255.

[openjdk]

@kimbarrett Pushed as commit bc7c255.

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