const runtime.gcBackgroundMode

4 uses

	runtime (current package)
		mgc.go#L567: 	gcBackgroundMode gcMode = iota // concurrent GC and sweep
		mgc.go#L679: 	mode := gcBackgroundMode
		mgc.go#L753: 	if mode != gcBackgroundMode {
		mgc.go#L820: 	if mode != gcBackgroundMode {