Update to rustix 0.26.2. (#3521)

This pulls in a fix for Android, where Android's seccomp policy on older
versions is to make `openat2` irrecoverably crash the process, so we have
to do a version check up front rather than relying on `ENOSYS` to
determine if `openat2` is supported.

And it pulls in the fix for the link errors when multiple versions of
rsix/rustix are linked in.

And it has updates for two crate renamings: rsix has been renamed to
rustix, and unsafe-io has been renamed to io-extras.

crates/cache/src/worker.rs

@@ -256,7 +256,7 @@ impl WorkerThread {
 
         const NICE_DELTA_FOR_BACKGROUND_TASKS: i32 = 3;
 
-        match rsix::process::nice(NICE_DELTA_FOR_BACKGROUND_TASKS) {
+        match rustix::process::nice(NICE_DELTA_FOR_BACKGROUND_TASKS) {
             Ok(current_nice) => {
                 debug!("New nice value of worker thread: {}", current_nice);
             }