internal/rosa: configurable architecture

This enables curing via binfmt.

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

internal/rosa/tamago.go

@@ -1,10 +1,6 @@
 package rosa
 
-import (
-	"runtime"
-
-	"hakurei.app/internal/pkg"
-)
+import "hakurei.app/internal/pkg"
 
 func (t Toolchain) newTamaGo() (pkg.Artifact, string) {
 	const (
@@ -26,7 +22,7 @@ chmod -R +w ..
 
 sed -i \
 	's,/lib/ld-musl-`+linuxArch()+`.so.1,/system/bin/linker,' \
-	cmd/link/internal/`+runtime.GOARCH+`/obj.go
+	cmd/link/internal/`+arch+`/obj.go
 sed -i \
 	's/cpu.X86.HasAVX512VBMI/& \&\& cpu.X86.HasPOPCNT/' \
 	internal/runtime/gc/scan/scan_amd64.go