Add C23 keywords and types

[eisenwave]

Changes

This PR adds a few keywords that have been introduces in C23. Firstly, C now also has constexpr and the preprocessor got #elifdef and #elifndef. See https://en.cppreference.com/w/c/23.

Secondly, there are numerous extended floating point types (not yet documented on cppreference). See N3096 H.5.1 Keywords.

Checklist

• [x] Added markup tests, or they don't apply here because this is a simple expansion of the keyword list
• [x] Updated the changelog at CHANGES.md

[joshgoebel]

You can merge or rebase on latest to get newest changelog.

[github-actions[bot]]

Build Size Report

Changes to minified artifacts in /build, after gzip compression.

5 files changed

Total change +111 B

View Changes

file	base	pr	diff
es/core.min.js	8.2 KB	8.2 KB	+3 B
es/highlight.min.js	8.2 KB	8.2 KB	+3 B
es/languages/c.min.js	1.86 KB	1.91 KB	+50 B
highlight.min.js	8.23 KB	8.23 KB	+3 B
languages/c.min.js	1.87 KB	1.92 KB	+52 B