[RFC]: update math/base/special/atanh according to the FreeBSD implementation

[gunjjoshi]

Description

This RFC proposes updating the C implementation for math/base/special/atanh, according to the FreeBSD implementation.

We need to convert the floating-point value to a word and then perform integer calculations, as given in the original FreeBSD implementation.

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Checklist

• I have read and understood the Code of Conduct.
• Searched for existing issues and pull requests.
• The issue name begins with RFC:.