chore: fix C lint errors

[ujjwalv01]

Resolves #13275.

Description

What is the purpose of this pull request?

This pull request:

• Fixes a C linting style error in @stdlib/number/float64/base/signbit by declaring the x array as a const array in example.c.

Related Issues

Does this pull request have any related issues?

This pull request has the following related issues:

• Fix C lint errors #13275

Questions

Any questions for reviewers of this pull request?

No.

Other

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No.

Checklist

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

• Read, understood, and followed the contributing guidelines.

AI Assistance

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• No

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• Code generation (e.g., when writing an implementation or fixing a bug)
• Test/benchmark generation
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[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
number/float64/base/signbit	$\\color{green}169/169$ $\\color{green}+0.00\\%$	$\\color{green}7/7$ $\\color{green}+0.00\\%$	$\\color{green}2/2$ $\\color{green}+0.00\\%$	$\\color{green}169/169$ $\\color{green}+0.00\\%$

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