internal/pkg: exclusive artifacts

This alleviates scheduler overhead when curing many artifacts.

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

internal/rosa/kernel.go

@@ -8,6 +8,7 @@ import (
 
 // newKernel is a helper for interacting with Kbuild.
 func (t Toolchain) newKernel(
+	exclusive bool,
 	patches [][2]string,
 	script string,
 	extra ...pkg.Artifact,
@@ -16,7 +17,7 @@ func (t Toolchain) newKernel(
 		version  = "6.18.5"
 		checksum = "-V1e1WWl7HuePkmm84sSKF7nLuHfUs494uNMzMqXEyxcNE_PUE0FICL0oGWn44mM"
 	)
-	return t.New("kernel-"+version, slices.Concat([]pkg.Artifact{
+	return t.New("kernel-"+version, exclusive, slices.Concat([]pkg.Artifact{
 		t.Load(Make),
 	}, extra), nil, nil, `
 export LLVM=1
@@ -34,7 +35,7 @@ cd /usr/src/linux
 }
 
 func (t Toolchain) newKernelHeaders() pkg.Artifact {
-	return t.newKernel(nil, `
+	return t.newKernel(false, nil, `
 make "-j$(nproc)" \
 	INSTALL_HDR_PATH=/work/system \
 	headers_install