## Why
`IORingGroup` issues io_uring syscalls directly rather than linking `liburing`, so the package has
never been needed — but we ask operators to install it in the README, install it in CI, and check
for it in `build-tool`.
Verified against the **shipped** `IORingGroup` 1.0.9 assembly, not just the source:
| Symbol | Occurrences in `IORingGroup.dll` |
|---|---|
| `libc`, `libSystem.dylib`, `kernel32.dll`, `kernelbase.dll`, `ws2_32.dll` | present |
| `liburing` | **0** |
| `io_uring_queue_init` — liburing's entry point | **0** |
| `io_uring_setup` — the raw syscall | 1 |
If it linked liburing it would call `io_uring_queue_init` / `io_uring_submit`. It calls neither.
## What changes
Nine lines across three files, removing `liburing-dev` / `liburing-devel` from:
- `README.md` — both the dnf and apt prerequisite blocks
- `.github/workflows/build-test.yml` — both install steps
- `Projects/BuildTool/Prerequisites/NativeLibraryChecker.cs` — the cross-compile target text, the
apt and dnf package lists, and the `ldconfig` fallback map
Nothing else is touched. `zstd` and the `-dev` packages are a separate discussion and a separate PR.
## Risk
None to the build. `liburing` was only ever installed, never linked or loaded — removing it cannot
change resolution behaviour. `build-tool` builds clean.
This was found while investigating why Linux requires `-dev` packages at all; that fix lives in the
binding packages (modernuo/LibDeflate.Bindings#4, modernuo/Argon2.Bindings#13) and lands separately
once those publish. This piece is independent and unblocked, hence its own PR.
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