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

[Pranavchiku]

Description

What is the purpose of this pull request?

This PR adds C implementation for @stdlib/math/base/special/round

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@stdlib-js/reviewers

[Pranavchiku]

cc @kgryte @Planeshifter

[kgryte]

@Pranavchiku Note that you previously worked on a PR for this feature: #745

[Pranavchiku]

Reference implementation: https://tc39.es/ecma262/multipage/numbers-and-dates.html#sec-math.round

Not sure how much credible this source is, but aligns with other miscellaneous sources.

[kgryte]

@Pranavchiku That source is credible. That is the official ECMAScript specification from TC39.

[Pranavchiku]

I think this is ready to review.

[Planeshifter]

Looks good to me, so let's get this in as the C implementation is required for the one of rempio2, which @gunjjoshi will be working on soon.