The wasi-libc is sensitive to the version of clang that is used to build it. That's because one of the build assertions checks for a list of pre-defined macros, and that list tends to change depending on the version of the compiler being used. Since any deviation from the expectations will fail the build, this check needs to be adjusted with each new version of clang that is used to build it.

The steps to fix this should be:
1. Update to the latest Fedora version OR pull the relevant adjustment commits from wasi-libc upstream.
2. Set explicit upper bound on `BuildRequires: clang` (e.g. `BuildRequires: clang <= 20`) to notify us that the package will need changes on clang updates.