internal/rosa: early toybox variant

This is a variant of toybox with unfinished tools enabled, for artifacts that will end up in a dependency loop without them.

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

internal/rosa/kernel.go

@@ -35,7 +35,7 @@ cd /usr/src/linux
 }
 
 func (t Toolchain) newKernelHeaders() pkg.Artifact {
-	return t.newKernel(0, nil, `
+	return t.newKernel(TEarly, nil, `
 make "-j$(nproc)" \
 	INSTALL_HDR_PATH=/work/system \
 	headers_install