chore: fix C lint errors

[Shivam-1827]

Resolves #6005

Description

What is the purpose of this pull request?

This pull request:

• Fixes a C linting issue in lib/node_modules/@stdlib/math/base/special/roundn/src/addon.c .
• Resolves a style issue where the local variable stdlib_base_roundn was incorrectly formatted or defined, leading to linting failures in the automated workflow.

Related Issues

Does this pull request have any related issues?

This pull request:

• Resolves Fix C lint errors #6005

Questions

Any questions for reviewers of this pull request?

No

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

The linting failure was detected in the automated C Linting workflow run on 2025-03-13.
Workflow details:

• Run: https://github.com/stdlib-js/stdlib/actions/runs/13823886807
• Type: C Linting
• Date: 2025-03-13 00:13:23 UTC

The specific error was:

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
math/base/special/roundn	$\color{red}276/279$ $\color{green}+98.92\%$	$\color{green}22/22$ $\color{green}+100.00\%$	$\color{red}1/2$ $\color{green}+50.00\%$	$\color{red}276/279$ $\color{green}+98.92\%$

The above coverage report was generated for the changes in this PR.

[kgryte]

Hello, and thank you for your contribution; however, your proposed changes do not actually address the lint error. The lint error was addressed in #6194. As such, I'll go ahead and close.

cc @Planeshifter