internal/pkg: per-cache SCHED_IDLE

This is cleaner than setting it globally, and is impossible to race.

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

cmd/mbf/main.go

@@ -88,10 +88,12 @@ func main() {
 		} else if base, err = check.NewAbs(flagBase); err != nil {
 			return
 		}
-		cache, err = pkg.Open(ctx, msg, 0, flagCures, base)
+
+		var flags int
 		if flagIdle {
-			pkg.SetSchedIdle = true
+			flags &= pkg.CSchedIdle
 		}
+		cache, err = pkg.Open(ctx, msg, flags, flagCures, base)
 
 		return
 	}).Flag(