Overriding `binaries` in a platform block doesn't seem to work

For podman I tried:

```hcl
binaries = ["podman"]

platform "darwin" {
source = "https://github.com/containers/podman/releases/download/v${version}/podman-remote-release-darwin_${arch}.zip"
strip = 1
binaries = ["usr/bin/podman"]
}
```

And it attempted to use the top level `binaries` attribute.

Reproduce the issue with the shown Hermit configuration, then trace how the top-level and platform-level `binaries` attributes are parsed and selected. Done means the `darwin` platform uses `usr/bin/podman` rather than the top-level `podman` value.

Written by the indexing model from the issue text.