internal/rosa: configurable architecture

This enables curing via binfmt.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/busybox.go

@@ -5,7 +5,6 @@ import (
 	"io"
 	"net/http"
 	"os"
-	"runtime"
 	"time"
 
 	"hakurei.app/fhs"
@@ -88,7 +87,7 @@ func (a busyboxBin) Cure(t *pkg.TContext) (err error) {
 // the https://busybox.net/downloads/binaries/ binary release.
 func newBusyboxBin() pkg.Artifact {
 	var version, url, checksum string
-	switch runtime.GOARCH {
+	switch arch {
 	case "amd64":
 		version = "1.35.0"
 		url = "https://busybox.net/downloads/binaries/" +
@@ -101,7 +100,7 @@ func newBusyboxBin() pkg.Artifact {
 		checksum = "npJjBO7iwhjW6Kx2aXeSxf8kXhVgTCDChOZTTsI8ZfFfa3tbsklxRiidZQdrVERg"
 
 	default:
-		panic("unsupported target " + runtime.GOARCH)
+		panic("unsupported target " + arch)
 	}
 
 	return pkg.NewExec(