const runtime.gcBackgroundMode

4 uses

	runtime (current package)
		mgc.go#L510: 	gcBackgroundMode gcMode = iota // concurrent GC and sweep
		mgc.go#L618: 	mode := gcBackgroundMode
		mgc.go#L681: 	if mode != gcBackgroundMode {
		mgc.go#L739: 	if mode != gcBackgroundMode {