This is a great list, it looks useful!
In addition to clib[1] mentioned in this list, there's also CCAN[2]. It's another collection of small C libraries, but unlike clib and this list, the libraries are maintained as a single project (for better or worse).
I'd love to see some more convergence on library search and package management for C. I was glad to see clib and CCAN consider coordinating.[3] Hopefully that effort will eventually bear fruit.
1. https://github.com/clibs/clib 2. https://ccodearchive.net/ 3. https://github.com/clibs/clib/issues/69