feat: add C implementation for math/base/special/floorsd

[gunjjoshi]

Description

What is the purpose of this pull request?

This pull request:

• adds C implementation for math/base/special/floorsd.

double stdlib_base_floorsd( const double x, int32_t n, int32_t b );

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves a part of [RFC]: Add C implementations to base special math functions (tracking issue) #649.

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.

• I have removed some of the test cases which were not relevant for the C implementation.

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

[Planeshifter]

LGTM!