feat(tvix/build), add OciBuildService, the old way r/8744

This is just patchset 10 of CL10855, before the color_eyre changes,
rebased to the tvix_castore api.

Change-Id: If4b42412ff8568058908cda971ad7d6f2d9f9b7b

---
This provides a build service invoking runc. It can be used by using the
`oci://$path_to_some_tempdir` builder URL for now.

For now, it can be tested as such:

```
BUILD_SERVICE_ADDR=oci://$PWD/bundles target/debug/tvix
let pkgs = (import <nixpkgs> {}); in builtins.readDir pkgs.perl
```

readDir is to actually trigger IO into the store path (which triggers
the builds).

For now it fails due to missing reference scanning (see followup CLs).

Change-Id: I09b40e410114ce69966a41a0e3c33281b859e443
Reviewed-on: https://cl.tvl.fyi/c/depot/+/12526
Autosubmit: yuka <yuka@yuka.dev>
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/tvix/build/build.rs b/tvix/build/build.rs
index fe230cbeca8a..909d6bab0875 100644
--- a/tvix/build/build.rs
+++ b/tvix/build/build.rs
@@ -30,5 +30,7 @@ fn main() -> Result<()> {
                 Some(proto_root) => proto_root.to_str().unwrap().to_owned(),
                 None => "../..".to_string(),
             }],
-        )
+        )?;
+
+    Ok(())
 }