internal/pkg: exclusive artifacts

This alleviates scheduler overhead when curing many artifacts.

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

internal/rosa/cmake.go

@@ -13,7 +13,7 @@ func (t Toolchain) newCMake() pkg.Artifact {
 		version  = "4.2.1"
 		checksum = "Y3OdbMsob6Xk2y1DCME6z4Fryb5_TkFD7knRT8dTNIRtSqbiCJyyDN9AxggN_I75"
 	)
-	return t.New("cmake-"+version, []pkg.Artifact{
+	return t.New("cmake-"+version, false, []pkg.Artifact{
 		t.Load(Make),
 		t.Load(KernelHeaders),
 	}, nil, nil, `
@@ -59,6 +59,9 @@ type CMakeAttr struct {
 
 	// Override the default installation prefix [AbsSystem].
 	Prefix *check.Absolute
+
+	// Return an exclusive artifact.
+	Exclusive bool
 }
 
 // NewViaCMake returns a [pkg.Artifact] for compiling and installing via CMake.
@@ -94,7 +97,7 @@ chmod -R +w "${ROSA_SOURCE}"
 	}
 
 	sourcePath := AbsUsrSrc.Append(name)
-	return t.New(name+"-"+variant+"-"+version, stage3Concat(t, attr.Extra,
+	return t.New(name+"-"+variant+"-"+version, attr.Exclusive, stage3Concat(t, attr.Extra,
 		t.Load(CMake),
 		t.Load(Ninja),
 	), nil, slices.Concat([]string{