internal/pkg: pass impure job count

This is cleaner than checking cpu count during cure, it is impossible to avoid impurity in both situations but this is configurable.

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

cmd/mbf/main.go

@@ -72,6 +72,7 @@ func main() {
 	var (
 		flagQuiet bool
 		flagCures int
+		flagJobs  int
 		flagBase  string
 		flagIdle  bool
 
@@ -99,7 +100,7 @@ func main() {
 		if flagHostAbstract {
 			flags |= pkg.CHostAbstract
 		}
-		cache, err = pkg.Open(ctx, msg, flags, flagCures, base)
+		cache, err = pkg.Open(ctx, msg, flags, flagCures, flagJobs, base)
 
 		return
 	}).Flag(
@@ -110,6 +111,10 @@ func main() {
 		&flagCures,
 		"cures", command.IntFlag(0),
 		"Maximum number of dependencies to cure at any given time",
+	).Flag(
+		&flagJobs,
+		"jobs", command.IntFlag(0),
+		"Preferred number of jobs to run, when applicable",
 	).Flag(
 		&flagBase,
 		"d", command.StringFlag("$MBF_CACHE_DIR"),